I encountered an error after installing the app on the Oculus Quest Pro. I start it and try to connect to the server using SignalR, this error message appears:
paste error message here
If I run the app in debug directly from Unity I have no error and it connects to the server.
It looks like you did not paste the actual error message in your post.
Usually, if something works in the Editor but not on device, it might be due to missing Android specific plugins or libraries. Although, it looks like other users are having issues with SignalR on Android in Unity. There might be a fix at the bottom of the thread.
This dev ended up using this asset from the Asset Store.