Reposting from pinned Troubleshooting discussion to a separate discussion for visibility.

Thank you Valve for your efforts on ARM support!

I have two questions:

1. Is there a way to control BT settings from Steam Link, even if it is not "officially supported"?

I know the FAQ says that Bluetooth(BT) is not supported on Rpi, but I know for a fact that I can connect a BT controller with my Rpi4 from either the Desktop Environment on Raspbian Buster or from the Retropie-Setup script and have it work from Steam Link.

I can control Steam Link with HDMI CEC, but not the Desktop Environment or RetroPie. so if I want to use a BT controller that is not currently paired, my only option is to also connect a keyboard so I can control BT settings.

Alternatively, my problem could be solved if I could control BT settings with HDMI CEC in some other way.

2. How do I troubleshoot video latency not related to network or screen configuration?

I have tested Steam Link on Rpi4 in 2 setups, but for one setup I observed unacceptable video latency. This setup involved the game Destiny 2 running on a modern Windows 10 laptop. The other setup with acceptable video latency involved the game Monster Hunter World: Iceborne, running on a PC with a Radeon 5700XT GPU.

I ran the first setup in someone else's home so I cannot troubleshoot that setup at this time, but I know there were no network problems (wired connection with a successful connection test for 90Mb/s) and seemingly no HDMI problems (the TV has no noticable latency while playing Nintendo Switch and Xbox One games over HDMI). I also verified that the HDMI connection was configured with a 'Gamer' setup (TV brand is LG). The game ran on a laptop with a wired connection, so when I placed the laptop next to the TV I could see on the laptop that the controller input latency from Steam Link was very fast.