so yeh i’m timing out when joining league lobbies, but multiplayer works just fine. Is this a common problem or is it just me? Its been doing it for the past few days 
Had it happen before for me.
Did you try a hard boot of Xbox. Iirc that worked for me.
yeh tried that, rebooted the router as well
When you did the hard reset of your xbox and router, did you make sure to unplug both from the wall for 1 minute? This is something that’s overlooked by some and can have a huge benefit if done correctly.
If there is no-one racing it will say joining lobby til time out I have found - although this may have nothing to do with what you are asking…