@Somnus @btx I got suggestions for further testings ... What I figured out is that if you set 1.1.1.1 and 8.8.8.8 as DNS-Servers for the WAN interface, also the LANs (which are set to DNS auto) work...

My solution: I run the omada controller on a vps - nothing fancy is required (in my case I have a local vps with 2CPUs, 2GB Ram and 10GB HDD). The omada controller is installed as a docker instance....

@btx to be honest, I still believe that I miss something - such basic functions should work out of the box ... specially for a company with networking knowledge and capabilities like TP-link their...

@btx thx for your answer. I totally agree, it is a shame that such a vital functionality does not even not run out of the box but that it is not even mentionied that there is a problem. concerning...

@Somnus thx for the info. It is really weird that by default the ip address of the gateway is published to the clients and the gateway does not run a DNS Server. Forwarding the ip of the upstream DNS...

I bought this router to get to know the omada system. Right from the beginning, I had issues as all devices told "no internet connection" - ping to a IP address worked, however the dns service didn't...