docs: packet loss and linux controller (LizardByte#2514)

Co-authored-by: ReenigneArcher <[email protected]>

docs/source/troubleshooting/general.rst

@@ -37,3 +37,19 @@ NvFBC, NvENC, or general issues with Nvidia graphics card.
   - You can usually bypass the restriction with a driver patch. See Keylase's
     `Linux <https://github.com/keylase/nvidia-patch>`__
     or `Windows <https://github.com/keylase/nvidia-patch/blob/master/win>`__ patches for more guidance.
+
+Controller works on Steam but not in games
+------------------------------------------
+One trick might be to change Steam settings and check or uncheck the configuration to support Xbox/Playstation
+controllers and leave only support for Generic controllers.
+
+Also, if you have many controllers already directly connected to the host, it might help to disable them so that the
+Sunshine provided controller (connected to the guest) is the "first" one. In Linux this can be accomplished on USB
+devices by finding the device in `/sys/bus/usb/devices/` and writing `0` to the `authorized` file.
+
+Packet loss
+-----------
+Albeit unlikely, some guests might work better with a lower `MTU
+<https://en.wikipedia.org/wiki/Maximum_transmission_unit>`__ from the host. For example, a LG TV was found to have 30-60%
+packet loss when the host had MTU set to 1500 and 1472, but 0% packet loss with a MTU of 1428 set in the network card
+serving the stream (a Linux PC). It's unclear how that helped precisely so it's a last resort suggestion.