Every multiplayer race i've started today has been disconnected.

Several league races. And in the multiplayer hoppers. I get at least halfway in, then I’m booted out without fail. ‘disconnected from session’. But then I can get right back in watch the race I was just booted from.

Restarted the game: no good.
Restarted PC: no good.
Rebooted router: no good.

Any guesses?