Oenwrt 21.02 - davdroid - domain access

First of all, I am not sure if this is the correct help section, if not, please advice.
I changed my router with an OPENWRT 21.02.
Since that change, nexcloud server works well but I am unable to access it from within my LAN.
I am aware of the loopback issue. And I dont want to use NCP as my DNS as its a RPi and I like to add less stress as possible.
I also have VPN to PIA setup at router and PiHole on a separate raspberry pi.
I can make an exception on the pihole for my lan to access the domain name Vs the local IP address. that works.

my android phone uses (of course) the nextcloud APP. that needs DavDroid for contacts and calendar sync.
Since I a changed my router with a OpenWRT, davdroid keeps giving a bad request 400 using my correct email address but all the certification details refer to the openwrt router and not my Nextcloud server.
that I cant figure out how to fix.
Any one can help me out here?