I did a search for banning but most of the results were on how to ban or why to ban someone, so here is my new suggestion.

Here's the situation that brought this to my attention. I was racing as a non-leaguer in a league race. One of the league players was seriously lagging. All the cars behind him slowly filter past but me. After about 2 laps of giving him a wide birth and losing about 2 seconds a lap, I decided to try a fairly safe pass in a braking zone. Of course, just as I decide to pass he lags into invisibility. Suddenly I hit.... nothing. Of course it is him, and he reappears as he spins off into the grass. As I'm trying to limp back to the pits, I am suddenly looking at the server selection screen, along with a message "connection lost".

Now, as I was having no lag issues (none of the other cars in the line were lagging but him) I can only assume I did not actually "lose" the connection. I'm guessing he banned me. (Can only one person ban if they have permission? I don't know the rules on banning...)

Anyway, my suggestion is that instead of a connection lost message, it says you have been banned. Perhaps you could also add an input area where the banner could inform the banee of exactly why they are being banned.

One person can kick or ban you if they have admin rights to the server. It's possible that happened in your case. Being a league server it's quite probable that an admin was online at the time.

Did you try and re-join that server? I'm not actually sure if you get a "you have been banned" message if you try and re-join a server you got banned from. It's possible the whole thing crashed and everyone got booted, or you just got a random disconnect. I have a pretty quick connection myself but still occasionally suffer the odd unexplained disconnection.