Can't start multiplayer game

First of all, this post is for my steam account. I have no idea why this forum always ask me to create a new forum profile when I tried login with my steam account, so I have to use my xbox account instead. this sucks.

So when the DLC released, I could see the new events, and play games normally. However after the next patch, I can no longer join any multiplayer games. It shows I’m connected to the server. I can still view mods, start single player games, and see status of my friends. But I can no longer see current events. And whenever I tried start searching for a multiplayer game, the button simply grayed out. When I tried to spectate my friends game, it shows error C04T09R03X-01 4F6736500ED for me.

I’ve tried reinstalled game, delete all local files in MyGames folder, the problem is still unsolved.

Funny thing is that I’m the only one bought the DLC among my friends, and I’m the only one having this trouble