There are a few servers that, for some strange reason, I can enter but not play in. I'll select the server from the main list, join the game, and then be stuck in what seems to be spectator mode while all of the players aren't moving at all. There's also a little message in the top corner of the screen that says something like 'waiting to join game.'

This only happens on a few servers, most notably the !Apaxteam (217.160.255.134) one.

Is there any way to fix this, or is it a server side problem?

Actually, I think it's both, but I'm not sure how to be rid of it. There're also some times when I'm stuck in Free Mode and I'm waiting to join the game, and I only can browse around the map, seeing nothing else...?

This happens to me as well, but when it does I just disconnect from that server, then reconnect and it's all fine again.

This is a known bug, just try rejoining, if not working...you cant get in, still 300 servers left

i think this happens when 2 ppl join a server at the same time but there is only place for one so the last one gets stuck in spectator mode.

When this happened to me I think i was that last person to get in the server, so i'm thinking that another person came in at the same time, which caused me to stay in spectator mode. But most of the time just try going into the server again, or go into another one. There are at least, 150 at all time almost.