I was testing only on wlan, tried it with cellular and it actually works as it should.
So I tried a different wlan, tethered over a different phone, and it still all works.
But still not with my original wlan. So I delet it and connect new to it, still doesn't work. Then I opened a guest wlan on the same router and it works. Back again to the normal network, still does not work.
Looked through my router but there's all the same.
Then I noticed that my phone doesn't get an IP adress while connected to my normal wlan just three IPv6. If I connect to the guest network it does not only get those three but also a normal IP adress.
the network setting is on DHCP, there's no special rule set in the router for my phone as the mac adress is random as standard setting. I changed it to fixed but still didn't get an IP adress. Other devices on that network work fine.