Pi4 with Amp2 and OS64, ethernet connection. I have the OS setup and running, installed Plexamp via extensions, go to Sources, click on Setup Plexamp, and I get ERR_CONNECTION_REFUSED.
I do have another plexamp instance running on another pc as well as two Plex media servers, they are all working fine. I dont think that would mess anything up, just trying to disclose stuff.