@anoncontainer 

How do you solve that issue now?

  @Alexandre. 

At the moment I just manually edit the DNS per device on the guest network

If the device frequently connects to the network I assign a static IP with my router. If you assign a static IP you can manually define DNS on a per device

basis.

  @anoncontainer 

I had conversation on that topic with someone and suggested workaround. Here is what we discussed.

Have second DNS service and connect it to Guest Network SSID. It could be separate box or same if your current DNS host has WiFi network card. If same, configure DNS service answer queries on both IP addresses: wired from Main and wireless from Guest. I know you can do that with BIND, for example.

You now have two IP addresses for DNS service: one of each reachable on Main and on Guest networks, another is not. Configure router with these two IP addreses as your primary and secondary DNS. Most devices should be able to handle properly primary/secondary DNS with one of them down.

  @Alexandre. 

Thank you for your suggestion.
The issue is when the guest network is isolated. When you enable isolation on the guest network the devices connected to the guest network can not talk to each other. Your only option is to use a DNS that is reachable from WAN.

anoncontainer wrote

 The issue is when the guest network is isolated. When you enable isolation on the guest network the devices connected to the guest network can not talk to each other. Your only option is to use a DNS that is reachable from WAN.

  @anoncontainer 

You are correct. Just tested it: can't even ping between two devices on Guest network when isolation is enabled, can ping when it is disabled.

That means, workaround I mentioned won't work.

Hi, I requested this a couple of years ago... https://community.tp-link.com/en/home/forum/topic/259432 

@anoncontainer 

Yes, I want this also.