Please don't use port 5556 in Rider.
Android adb scans 5554+ and thinks it's an emulator: http://stackoverflow.com/questions/3152681/android-emulator-5554-offline
Then when trying to debug in Unity3D on Android it fails saying "Unable to retrieve device properties." because Unity isn't smart enough to just deploy to one device.
The workaround is to close Rider before running Unity on Android.