Title is misleading, Unable to join any games, which is false since I just loaded into Jailbreak just fine. The servers are just bugged right now/bogged down as usual on Fridays/Weekends. Or it may be a bug with the rejoin core gui. Still not ROBLOXCRITICAL since the games are still playable and nothing is broken. See:
Preventing all players from connecting to a game
If this said 0 players, then yeah this would be ROBLOXCRITICAL.