@Dekel you ever get a real answer to this?

My Pi-Hole needs this to resolve internal IP addresses.

I suppose I could check whether the `domain-name` or `domain-search` options gets set by the DHCP server,and then take it from there, but I think that the Deco's configuration options are actually slightly idiotic in its rather arbitrary limitations.

@eroux No I didnt, I also want to resolve Internal IPs and dont know how to find it.

@Kevin_Z  I was asking for the domain name not the IP address, See:

@Dekel 

I'm looking to do the same thing.

I'll keep searching and post back here if I find anything.

An online manual appears to suggest it might be possible, but perhaps is slightly misleading and instead referring to DDNS..?

https://www.manualslib.com/manual/1280406/Tp-Link-Deco-M5.html?page=12&term=domain&selected=1

Advanced Features

Additional features are available under the Advanced menu. You can modify WAN settings (IPv4 & IPv6), control Deco's LED and turn notifications off

and on, easily create a domain name for your Deco, set up port forwarding rules to make your local computers accessible to other devices over the

internet, reserve the same IP address for a specific device, and change the working mode.