Hey thanks for the quick answer!
I also tried all kinds of SSID names, security protocols.
That with the isolation was new to me. Havent found any option like that though.
I was some time ago able to play games lan multiplayer with one pc lan connected the other wlan.
so I dont know if thats the reason.
but indeed I also do not see my other pcs that are wired with lan to the 2nd router in the network of my wlan pc..
thanks again for the help!