I am running 2 devices as dumb wifi router, I was wondering if i have to set a DNS
server on these devices via Use custom DNS servers to the IP address of my main router or do I have to leave it empty?
at the moment i am not able to ping /resolv any ulr from a terminal on these 2 devices. Use custom DNS servers is empty.
No. Either set them up per the wiki with static ips. Or on the main router setup DHCP reservations for those mac addresses and then leave the AP's as DHCP on their "WAN" side. You will still need to configure the APs for wifi and remove firewall etc as per the wiki.
I tend to prefer my AP's be DHCP reserved so i can move them around networks if required. That way i only need to configure the AP once. Otherwise with a static you would have to take it down to reconfigure its static ip if you change your networks etc. (eg segmenting guest networks etc.)
APs dont require DHCP servers. Only if you running big networks etc. What you want them to do is provide effectively a WIFI area but your router manages DHCP and networks.
The DNS setting on a dumb AP only affects the OpenWrt OS itself. And it has to be set for OpenWrt to access the Internet for NTP or to fetch packages or updates. But the internal DNS setting has no effect on how wifi clients will get their DNS. That will always be bridged through to the main network.
its strange, i just figured out all my ios devices works fine, but the android is an issue.
I cant even ping that domain name; ping app crashed, and homeasssistant cant reach that url at all so no idea.