Can't join any multiplayer server since 1.17 but I can still join singleplayer worlds. Other players on the server can and the server is definitely in 1.17. I tried all possible servers that I was in and all of them had the same problem.

Attempts to fix:
I had a look at my firewall.
I restarted my computer.
I logged out and back in.
I completely deleted Minecraft and reinstalled it.
I waited a few days and then tried restarting my computer and logging out and in. 

(behind the light blue bar is some server information).