@Mihu 

 

With Deco, this behavior is by design. Deco uses DNS queries for Internet health check, if DNS queries fail Deco assumes Internet is down.

 

You need to figure how to improve your DNS server or service uptime, and how to bounce it automatically when it fails.

@Alexandre. 

 

But "internet down" doesn't mean "network down".

 

Why should Deco not relay ethernet traffic on the local network just because DNS fails?

 

Moreover, in AP mode, it's none of Deco's business whether internet is up or not, it's just supposed to give wifi access to the LAN.

@Mihu 

 

You are correct, and I think I made a mistake in assuming how Deco will behave when DNS service is down. When I tested Deco in AP mode behaviour, I turned off ISP Router which on my network is DNS/DHCP/Router. I haven't tried turning DNS service off alone. 

 

Can you clarify one thing for me: when DNS service down, how are you trying to reach DNS server to bounce it? Meaning: do you attempt to SSH to it from computer connected by Ethernet cable to router or from device connected to Deco wirelessly?

@Alexandre. 

 

The DNS server is a VM running on a host on the LAN. I should  have a number of ways to restart the service or the whole thing, eg:

 

1) Using the web management console of the host to access the console of the VM (fails, because the host is connected via the Deco which refuses/is unable to relay the traffic)

2) Using ssh from a remote location, through a NAT rule on the router direct to the VM (fails, for the same reason)

3) As for 2, but ssh into the host to reboot the whole thing (fails, for the same reason)

4) Using ssh on the LAN, direct to the VM (fails, for the same reason)

5) As for 4 but ssh into the host (fails for the same reason)

 

ROUTER === [PORT1] DECO [PORT2] === VM HOST

 

I can set it up a different way, but it seems like a design flaw that Deco gives up as soon as there is no DNS resolution if indeed that's what is happening.

 

@Mihu 

 

For #2 to #5 I have plausible explanation and general expectation it will fail, based on my tests with Deco mesh failing its Internet health checks.

 

I am not sure why #1 fails (accessing VM from its own host server by IP address), and I may have asked you to run more tests for me, but I have a solution for you for about $20, so why bother with anything else?

 

As long as you are willing to spend $20 for no frills 5-port gigabit networking switch, or have one to spare, this should work for Deco running in AP more:

 

[MODEM]

=

=

=

[ROUTER]

=

=

=

[SWITCH] = = = [MAIN M9+] --- [SLAVE M9+]

=

=

=

[SERVER WITH DNS]

 

You'll be able to access DNS server from remote location through NAT rule on a Router.

 

You can put switch side by side with Main Deco, making solution not dependent on Ethernet wiring and hardware placement considerations. Yes, I know, perhaps not the most elegant solution, but it should work. 

 

This is, of course, if you can't just bring [SERVER WITH DNS] to where [ROUTER] is and wire DNS server directly to one of free Ethernet ports on Router.

 

---------------------------

 

Unless you've figured something like this already and only brought issue to that forum to get TP-Link Support attention as a software feature request or bug report.

 

---------------------------

@Alexandre. 

 

#1 fails because the vm host is headless - the gpu is passed through to a VM for hardware transcoding. The only way to drive the host is via ssh, or using the web management console for the hypervisor. Both fail because Deco cannot reach the internet and stops relaying ethernet traffic.

 

"This is, of course, if you can't just bring [SERVER WITH DNS] to where [ROUTER] is and wire DNS server directly to one of free Ethernet ports on Router."

 

The network topology is beyond the context of this discussion, but yes - I want the DNS server and the Deco-provided wifi connected to the same port on the router. Deco should be able to act as a switch in AP mode with or without DNS resolution. 

 

"Unless you've figured something like this already and only brought issue to that forum to get TP-Link Support attention as a software feature request or bug report."

 

Yes.

 

 

@TP-Link 

 

TP-Link wrote

 

Mihu wrote

@Alexandre. 

 

The DNS server is a VM running on a host on the LAN. I should  have a number of ways to restart the service or the whole thing, eg:

1) Using the web management console of the host to access the console of the VM (fails, because the host is connected via the Deco which refuses/is unable to relay the traffic)

2) Using ssh from a remote location, through a NAT rule on the router direct to the VM (fails, for the same reason)

3) As for 2, but ssh into the host to reboot the whole thing (fails, for the same reason)

4) Using ssh on the LAN, direct to the VM (fails, for the same reason)

May I know where the LAN SSH client is? connecting to the Deco, or the main DHCP router?

5) As for 4 but ssh into the host (fails for the same reason)

@Mihu 

 

In that situation, the ssh client could be:

 

a) The router itself (ssh to the underlying OS, and from there ssh out to the DNS VM, via the Deco's ethernet ports)

b) A client connected to a second wifi network using a separate port on the router. This uses a second pair of Deco M9+ and works perfectly well since the DNS on that network is more robust.

 

In all situations however, the Deco pair that experiences DNS failure goes solid red and will no longer relay ethernet traffic, so ssh cannot work.