I am using a quite custom setup:
[PC Win 10 x64 with AMD Radeon RX-580] --> HDMI --> [Yamaha RX-V367 AC Reciver] --> HDMI -> [Samsung TU7079 TV]
Problem is, that I am not able to set any resolution but 800x600 pixels - at least when the system ist started. While booting I get 1080p (Windows bootscreen and BIOS). At the moment the login screen appears: 800x600.
So I bootet with Linux (Kubuntu). No Problems, 1080p works. Other resolutions work too. Other devices [instead of the PC] e.g. a Chromecast, a PS4 and funny: My girlfriends PC with a Intel GMA work great.
So in my intention it is a driver relatet problem. I am using the 20.4.2 version of the driver.
I tried to set the resolution custom. But whatever I try, every resolution is "unsupported".
Here some screenshots:
Sorry, everything is in german....