Hi @RaRu 

Thanks for posting in our business forum.

RaRu wrote

  @Clive_A 

 

Hi, Thanks for your reply.

 

How should I check that: Does the WAN still get an IP address?

Since I can't log into router, it has no connection to controller, ping from WAN do not response.

 

Only one site crashes at the time. One crash do not cause a crast on the other site.

Ping to the default VLAN 1 GW IP, does it respond? Looks like the router crashed and died?

Hi @RaRu 

Thanks for posting in our business forum.

RaRu wrote

  @Clive_A 

 

On Site's router there is only one, default LAN - 192.168.100.1/24 and router's IP address is 192.168.100.1 which responds.

DHCP IP still assigned, not showing up as 169.254.X.Y. And pinging to the 192.168.100.1 works as well. That'd be a VPN problem in which tunnel fails.

Not the router crashes. As for the setup where you have a S2S VPN, once the VPN tunnel is down, it'll affect the controller and readings on it.

Is that possible to backup your config and let us test with it?

I am prone to believe that the issue is about the ISP. If you have spare units, you can also test this under the local network as it creates a stable network environment.

Besides, possible to Wireshark on the WAN to monitor what caused the disconnection? Which you might need a full capture and filter the several parameters:

1. DNS resolution on the WAN is used to detect the online status. I explained this part in a KB article, which you can find helpful in determining whether this is actually a WAN issue.

2. IPsec related parameters. IKEV, IPsec and other values.

Hi @RaRu 

Thanks for posting in our business forum.

RaRu wrote

  @Clive_A 

 

Hi,

 

The router is connected to the controller via Internet, not via VPN. I can manually disconnect S2S VPN on the device and it still reports to controller.

 

Moreover, when the problem occurs, not only the intranet is not working, but also access to internet. If only VPN fails, then (in theory) Internet access should still work as usual on that device, but it is not.

 

I don't have spare unit, no. The problem occurs once a week or so, at random. Gathering Wireshark logs for whole week is almost impossible.

The only thing I have observed that (so far) daily reboots of router prevents this from reoccurring (one router is getting rebooted daily and so far there's no issue, second one is not getting reboots and is "crashing").

 

I can export the config, yes. How would you like to receive it?

Cloud access, we need that.

What's the WAN2 module you use? Do you have a specific model number?

Or RJ45 to SFP? Can you confirm?

If you replug the WAN port, will it recover the WAN connection? If you know.

Will get you a ticket later.

Hi @Clive_A 

Thank you so much for taking the time to post the issue on TP-Link community!

To better assist you, I've created a support ticket via your registered email address, and escalated it to our support engineer to look into the issue. The ticket ID is TKID241254733, please check your email box and ensure the support email is well received. Thanks!

Once the issue is addressed or resolved, welcome to update this topic thread with your solution to help others who may encounter the same issue as you did.

Many thanks for your great cooperation and patience!