Handling the Dreaded Synology DSM “Cannot Connect To The Internet” Error

I finally had a couple of seconds to rub together to try out the mixed-environment Synology backup workflow that I’ve been meaning to get around to, but needed to do some quick updates to some boxes that I have not used in a while. Little did I know that I’d have to postpone it, yet again.

[Update 2017.06.13. For this exercise I’m assuming you have your Synology connected to a router/switch, not directly attached to a computer. If you attach the Synology directly to a computer that is not running DHCP you will get a 169.254.X.Y address, it will not connect to the Internet and these instructions won’t work, I’m afraid.]

When you log into the DSM Control Panel, you’ll see a familiar flag connected to the icon, letting you know that there is an update to be made:

You've got updates!

You’ve got updates!

When you click on the update, the control panel will open up and you can see the little flag bounce at you:

Pick me!

Pick me!

When you click on the Update and Restore icon, what you should see is this:


Update at will, ensign.

Instead, sometimes you can get this:

Ah, crap. Now what?!

Ah, crap. Now what?!

(Eagle-eyed readers will notice that these last two screenshots are from two different machines. Fear not: it happened with both of them).

Ah, yes. The evil, “Connection failed. Please check your Internet Connection” error. This problem has confounded many a poor soul. Rumor has it that the only people to have successfully beaten this devilish problem are the Ancient Mayans, who also were able to count to 2012 and start over without panicking about the end of the world.

Now before you run screaming to the streets or try to wipe your Synology clean, here are a couple of things you can try.

First, navigate to the control panel if it’s not already showing (that’s the icon I showed up above). Then you want to find the icon labeled “Network.” It looks like a little house sitting on top of a sewer line (and if you know anything about networking, you’ll realize just how appropriate that is):


The screen that pops up will tell you what your network settings are. Most of these should be filled in for you. There is, however, two lines that you need to look at: The Default Gateway and the IPv6 Default Gateway.

Look at the pretty circles.

Look at the pretty circles.

You’ll notice a couple of things. First, there is no Default Gateway listed. This is bad. We’ll get to what these things mean in just a moment. For now, let’s fix this.

Default Gateways

Click on the “Edit” button next to the Default Gateway. It should look something like this:

I see you now!

I see you now!

Once the LAN configuration is populated (i.e., it shows up), you can click on OK. The Network control panel should now have this value next to it:

Where you been all my life?

Where you been all my life?

But what happens if it’s not there? Everybody panic!!

Wait, wait. No, that’s not right. Let’s try this instead. Click on the next tab over, the “Network Interface” tab. You’ll see at least one connection listed.

Getting closer...

Getting closer…

Go ahead and click on “Edit” with the interface highlighted, as it is in the picture above. Here is where your mileage may vary. If you have your Synology Diskstation set up to get its network configuration from your router, it will have “Get network configuration automatically (DHCP) chosen for you. Personally, I like to have my devices on static IP addresses, so I use the manual configuration option:

Why do it the easy way? Manual config all the way!

Why do it the easy way? Manual config all the way!

If you didn’t see the default gateway in the previous step, you may want to check to make sure that the checkbox is selected to “set as default gateway.”

One word of caution: Do not put in arbitrary numbers here. These numbers mean something, so if this is all Greek to you then simply keep the “Get network configuration automatically (DHCP)” checked and don’t worry about this stuff.

While we’re on this screen, however, we need to make some changes to the IPv6 settings as well. Fortunately, it’s just one tab over. There’s only one change you have to make here, and it’s an easy one:

IPv6 is a big bowl of "nope"... for now.

IPv6 is a big bowl of “nope”… for now.

Yup. Just turn IPv6 off.

So what does this stuff mean? The Synology needs to know where to find its way out of the network to see the world (fly! Be free, little Synology!). The Default Gateway is just that – it’s the gateway to the world (online, at least), and the “default” part of it means that this is where the Synology should look if it wants to communicate with the outside world. Since we want to know if Synology has an update that we need, and Synology is in the outside world, this Synology does not know where to go.

The second thing you’ll see is that the IPv6 default gateway does have an address listed. Yes, it’s the fe80::5a6d:8fff:fef6:a226 gibberish that’s next to the words “IPv6 default gateway.” Nifty how that works, eh?

When you turn it off, this default gateway should disappear, and it should look something like this:

Which way did he go, George?

Which way did he go, George?

DNS Servers

So, we figured out how to tell the Synology to find devices outside of our home network. This is the “if you don’t know where to go, go here” setting. But once the Synology goes there, then what?

The DNS Server is the place to do that. It’s a server that keeps track of what all these strange numbers mean. They’re the devices that you can ask to find out how to turn google.com into an address that the computers understand, and vice versa.

Speaking of Google, Synology recommends using their DNS server address as the “Preferred DNS Server,” so you should make your system look like this:

The Goobles to the rescue!

The Goobles to the rescue!

Now, in this case, you want to make sure that the numbers match exactly. The periods (full stops) and all. No spaces. You do not have to have an alternative DNS Server, but I put my default gateway as my alternative if, for whatever reason, Google’s DNS server doesn’t respond.

Here Goes Nothing

When I updated my two boxes, I had very different reactions from them. They both gave me the “Could not connect” error. What was even stranger was that on one of the boxes, I did not have to remove the IPv6 setting for it to work – a simple restart after fixing the default gateway and DNS server gave me complete connectivity. The other one, though, was a true PITA.

I tried using Synology’s QuickConnect, and it didn’t work either. Then, I had a bit of a minor success. I was able to turn on the NTP server (that’s the service that lets the Synology know what time it is, according to the US Government’s NIST time servers). Then, miraculously, QuickConnect worked. However, the DSM update continued to give me that error.

Then, about 5 minutes later, the DSM update was giving me what I needed to see:



My best guess is that the time it took for the routing tables to be updated took far longer than either the DSM user interface or my patience expected. I had restarted the box a couple of times in the interim, hoping that it would take, but I think I might have disrupted the population of the tables, and the DiskStation simply restarted the process again. I think that patience is far more useful a tool in this instance than I first thought.

Other Options

Update 2018.06.25. Several readers have written in to say that this has helped them figure out what’s going wrong, and others have offered suggestions for what have helped them fix the issue as well. I have not attempted these, but I’m leaving them here as a courtesy for the reader to attempt, should the above steps fail to resolve the issue.

  1. Change the admin account password. Every Synology has an “admin” account. Some people have had luck changing the password. It’s not clear why this is an issue; the best I can think of is that newer versions of DSM are requiring a stronger password for allowing incoming/outgoing traffic, but that’s just a guess. In any case, try changing the Synology “admin” account password.
  2. Modify DNS settings. I do not use the Synology’s DNS settings, so this was not an issue for me. However, another reader is using Synology’s RT1900ac router, and offered the following advice:For the DHCP server, “forward known DNS server” was disabled. Also, IPV6 was setup as AUTO in STATELESS mode. With these settings DSM update could not connect to the internet.Since the issue seems to be DNS related, I changed these two settings: a) I enabled “forward known DNS server”, and b) I changed my IPV6 setup to be stateless DHCPv6. I’m not sure which fixed the problem, but my DSM was immediately able find and install updates.
  3. Check your time zone/time server (NTP Server). If the date/time setting is out of whack, it can create issues.
  4. If the Diskstation switches to offline mode after a few seconds, try whitelisting the Synology server in uMatrix. DSM may detect that the browser won’t able to open the pages and switch to offline mode. The Synology update server may be found after that. Try pinging arbitrary addresses to double-check. (Thanks and h/t to Carsten Groß)

As I said, I have not attempted these fixes myself (hence no screenshots), but readers were kind enough to offer additional suggestions and if it helps you in your hour of need, please let me know. YMMV.

Synology’s Take

I contacted Synology’s tech support to find out why this might be happening, since there were no reports in the logs about what had happened during the update process. Here’s what I got, verbatim:

Upon further investigation I see there were some bugs in the past with a disappearing gateway, primarily if the connections were bonded during the upgrade. It was a bug that should be resolved now and should not typically happen.

Now, it is true that one of the Synology DiskStations I was updating had bonded network interfaces, but that was also the one that fixed itself faster. True, I was updating to DSM 6.0 so perhaps the fix was already being applied at that point too. The device that I have been using as an example, however, only had one network interface so there was no link aggregation (or “bonding”) going on.

Even so, after I run the backup tests in a mixed DSM 5.2/6.0 environment, I’ll be needing to update this box to 6.0, so I’m fully expecting to need to refer back to this blog again if/when I lose network connectivity!


I did read some additional messages in the user forums that permissions problems could be to blame for this issue, but it was not so in my case. My gut tells me that is a different issue – the problem here is connecting to the Synology servers in order to determine whether there is an update, and if so which one. Permissions issues would likely only result once it has been determined that an update exists and then issues would arise when trying to save it to a local directory on the Synology. That’s my gut take on it, however, and certainly not something I’d defend to the death.

In any case, I hope that this is somewhat helpful to people (including myself). If this works – or if it doesn’t work – please feel free to leave a comment and let me know. Anything I missed? Please feel free to offer another solution to help out. 🙂


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  • German February 28, 2017 at 13:14

    Thank you! been having trouble for a couple of hours on how to get the Synology to connect to the internet, your guide worked flawlessly 😀

    • J Michel Metz February 28, 2017 at 18:03

      Great! I’m glad it was helpful!

  • Justin April 20, 2017 at 06:45

    Thanks very much for this, solved the problem for me.

    • J Michel Metz April 20, 2017 at 08:37


  • Seb April 21, 2017 at 04:49

    Adding in google as the additional gateway fixed it for me, thanks.

    • J Michel Metz April 21, 2017 at 05:41

      Excellent. I’m glad this could be helpful.

  • RanRan May 2, 2017 at 14:34

    Awesome post and thank you, sorted this out for me!! Thanks again!

    • J Michel Metz May 2, 2017 at 14:50

      I’m very happy to hear that. Thanks for the feedback (it helps to know that people got use out of this).

  • Vyazhan May 4, 2017 at 05:41

    Hi there,

    despite following everything in your guide, I still can’t get it to work. The weird thing is that I am sure it worked just a couple of days ago. When checking my connectivity, I can connect to the NTP server to get my regional time as well as access the package center. My DNS is set to manually configured and to both google DNS and all the settings from the DHCP of the router seem correct too.

    However, despite all of this, it still shows me that it can’t connect, even though I actually downloaded the latest update just a day ago.

    Any advise what else could be the culprit?

    • J Michel Metz May 4, 2017 at 07:12

      Hi Vyazhan,

      There are, unfortunately, a few reasons beyond what’s listed here. Without being able to say for sure, there is a possibility that another device on your network (with DHCP) may have picked up the IP address normally associated with your DS. It’s rare, but it’s possible. All of my devices on my network are manually assigned IP addresses to avoid this from happening (it’s happened before).

      Another possibility is if there were something else that’s changed in the interim. For instance, if you were doing multiple changes in your network and the router turned on a firewall setting, for example (though it doesn’t sound like this is the case here).

      Since you can get to the NTP server, you’re obviously getting external connectivity. The question, then, is why you aren’t able to connect to the Synology servers. I’m afraid I’m at the end of my ability to troubleshoot from here, though. If you do happen to talk with Synology, please return here with any advice they give so that I can update this blog with any additional information.

      Thanks for reading, and I’m sorry I couldn’t be more help.

    • J Michel Metz May 4, 2017 at 10:01

      I just thought of something. It’s likely not to work, but I figured what the hell? It’s at least worth a try. While the DS is running, do an Ethernet cable pull. That is, detach the cable from the DS, wait for about 10 seconds, and then re-insert it in. It may take a while before the full process back and forth with the servers happens, but after 5 minutes or so we should see if it works or not.

      • Vyazhan May 4, 2017 at 10:26

        Heya, thanks for all the help 🙂 I just tried this but the issue persists unfortunately. I also tried rebooting and completely powering off for a few minutes and powering back on.

        I assigned the DS a static IP so this shouldn’t be a prob. Yeah, my knowledge is also at it’s end with this. As a final test I SSHed into the DS and tried to manually fetch the update but this failed too, but whenever I check with a different command than the main one, it actually shows me there is an update, so it’s just all weird…but what’s new 😀

        In case anyone wants to follow this further, there is the forum post here: https://forum.synology.com/enu/viewtopic.php?f=145&t=131143

        Thanks for trying to help, but this nut does not want to be opened easily it seems 😀

        • J Michel Metz May 4, 2017 at 10:33

          No, it doesn’t. I’ve also been looking around for answers today, seeing what I might have missed. It may also be a problem on Synology’s side, though, in which case we really are at the end of the line in terms of things we can actively do. 🙁

          • Vyazhan May 4, 2017 at 10:37

            You’re right. I have another Synology here and there it all works fine and dandy (which might have lured me into a wrong security of it being my fault 100%), but perhaps it is related to just a specific Synology DSM package Update (I got a DS1515+ that I access remotely which gives me the error, keeping in mind I had a local person observe the same issue).

            I will leave it for a few days and until then conclude that I have perhaps learned something in the process 🙂 Thanks again for all the super quick support and help, I and many others appreciate it!

          • J Michel Metz May 17, 2017 at 07:04

            Sorry for the late response – I didn’t get notification that you had replied.

            I *have* noticed that the different DSM versions per model can have some unexpected variances (I have 4 Synologies and sometimes the updates do different things). I hope Synology manages to regain some consistency.

            Glad that it could be helpful at some level. Good luck!

          • Vyazhan May 23, 2017 at 14:14

            No problem at all 🙂 So after a discussion with the support it seems that my custom installed version of /opt (optware) seems to have caused the difficulty. I haven’t gotten around to resetting my DSM yet (I use opt to get the CLI for the download station) but I am pretty sure that could be the culprit, especially since the other updates of the packages themselves work just fine.

            Either way, here is hoping we see the functionaltity for auto-resume in the Download Station anytime soon!

            Thanks again and good luck for all the others ending up on this blog! 🙂

  • Ed Kirton May 17, 2017 at 00:13

    Worked like a charm, thanks!

    • J Michel Metz May 17, 2017 at 07:02


  • jackeagle May 29, 2017 at 02:11

    Thanks this worked great for me as well- better than synology support!

    • J Michel Metz May 29, 2017 at 06:14

      Fantastic! Thanks for letting me know. 🙂

  • Richard Claridge June 9, 2017 at 22:50

    Hi, when editing the LAN IPv4 settings as per your instructions and inputting my gateway address in the ‘Gateway’ box, it becomes highlighted in red and tells me that some of my settings are invalid. R.

    • J Michel Metz June 11, 2017 at 12:21

      My apologies for the delay in approving. I was traveling and had no access to wifi.

      It’s difficult to troubleshoot like this, but my first guess would be to double check your entry for typos (commas instead of periods, for instance). Another thing you might want to check is whether or not your subnet mask is in the correct range.

      Hope this helps.


      • Richard Claridge June 12, 2017 at 01:26

        Hi J, thanks for the reply. Apart from checking that I didn’t enter any typos I’ve also been doing some digging around regarding your reply and my Synology IP address is 169.254.277.xx whereas my IP is 192.168.1.xx and the device is giving ‘The IP address and the default gateway belong to two different subnets’ message. Would the two very different IP ranges have something to do with it? Thanks R

        • J Michel Metz June 12, 2017 at 02:12


          Your Synology has a self-assigned address. This is also called “ZeroConf” or “Bonjour” addressing. It’s a way for the Synology device to be able to be found on the network when network settings are unknown (that is, for Synology Assistant to be able to find it on any local network).

          What you’ll have to do is change the Synology IP address to match the 192.168.1.xx address. Often times your home router will provide that address as a DHCP server. If you look above in the text of this article, you’ll see a screen shot there with the caption “Why do it the easy way?” See what your radio button is set to. If it’s set to “Get Network Configuration Automatically,” and it’s still giving you a 169.254.X.X address, try selecting the manual button, and then select it back again. What we want is for the same DHCP server that gives you your computer’s address (192.168.1.x) to give the Synology a 192.168.1.y address. Your subnet mask should be

          Speaking of your Synology Assistant, keep it handy. If you change your IP address and save the changes, it’s highly probable that you may lose connectivity as the network configuration resets. The Synology Assistant will help you get back to it.

          Let me know if that does the trick.

          • Richard June 12, 2017 at 18:17

            Hi J, thanks again. Switching from auto to manual didn’t work so I gave up. It wasn’t critical that it connected via my MacBook, just would have made it easier. My Synology Assistant couldn’t see my DS anyway. I decided to attach it to my Router directly and it I can now connect and it can get to the internet too, after all that :-). Thanks for your time in answering my queries. Cheers R.

          • J Michel Metz June 13, 2017 at 06:12

            Ah, it sounds like you had originally connected the Synology to the MacBook instead of the router/switch, which would explain why it gave itself a Bonjour address (the Macbook doesn’t have a DHCP server). Believe it or not, from the sounds of things, you have things set up the way you’re supposed to now. 🙂

            Congratulations on having a working system. Enjoy!

  • Mark June 17, 2017 at 23:00

    Time in regional settings was the problem for me – I was having issues syncing with Amazon Cloud storage and connecting to Synology backup. Having moved to a new time-zone the conflict was obviously preventing connectivity to these services. As soon as I amended to sync to NIST with my new region all external connectivity started to work again. Result!

    • J Michel Metz June 18, 2017 at 01:52

      Excellent advice. Thank you!

  • Brent June 21, 2017 at 08:42

    Thank you. I didn’t have to go through all of the steps, but your guide made it apparent that my synology was hanging on to my old default gateway IP address.

    • J Michel Metz June 21, 2017 at 08:55

      Great! I’m glad that it was helpful. Personally, I love it when the first clue gives me what I need so that I don’t have to go through all the rest of the troubleshooting steps (though, to be honest, that rarely happens…)

  • Nathan June 27, 2017 at 19:09

    Thanks mate, I was able to get Anitvirus and DSM updates working after following your guide.

    • J Michel Metz June 29, 2017 at 15:11


  • Al July 2, 2017 at 07:51

    Thanks – I spent all last night screwing with this, followed your steps this morning and I’m back up and syncing

    • J Michel Metz July 2, 2017 at 09:58

      I’m glad this was helpful. Thanks for letting me know. 🙂

  • Steel Cat July 16, 2017 at 03:44

    Tnx for this. I had my Preferred DNS Server set to my Gateway, and my alternate one to some IPv6 IP.
    I change that so Google was my first and Gateway the second. It started working instantly.

  • Robo July 27, 2017 at 08:42


    Migrated two Synology machines to a new network and both had updates failing with the “cannot-connect” issue.

    The IPV6 “Off” on my wireless adapter solved one of my update issues (DS215j)

    A second box (DS710+) with the same issue was fixed by changing the “admin” users password (required even though account is disabled).

    Great stuff!

    • J Michel Metz July 27, 2017 at 09:02

      Thanks for letting me know. I don’t know if it ever would have dawned on me to change the “admin” user password. I don’t remember seeing anything in the documentation about a connection between the two. I’ll add that to the main body of the post.

      Thanks again!

  • anselme July 31, 2017 at 14:26

    many thanks ! Mine was not on time, and ipv6 was not disabled.

    • J Michel Metz July 31, 2017 at 14:27

      Glad it was useful. 🙂

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