An undefined error occurred. error code: 1:3300J:DJ:9C-13561655840

I've also been having this problem for about 30 minutes, as has my brother who lives in a different state.

My girlfriend didn't quit out of the game from when we played earlier, and she is able to join servers without a problem. So the issue appears to be with the initial connection somehow. 

I just fixed it! 

Go to the EA app, click on the three horizontal lines on the top left corner, then help and App recovery.

Select clear cach and try to lauch the game after the restart.

Im on ps5 console,cant do your recovery stunt

Getting this error as well on Steam version