yep and I completly revoke my previous statement.

I did not realize that I booted into windows...

So the problem seems to be linux related as the problem still persists there.

Sorry for the confusion

actually I tried that already. I decreased the size of my blueprint library, but still had the same problem.

It seemed to be a MTU problem. With 0.15.31 and properly set MTU at my side (1500 instead of 1492 -_-) I can play.

I was able to play multiplayer a few releases ago, as I finished a 0.15 map already (I don't have the save anymore, but it should be < 0.15.14)

I will try to find out if I have any MTU related problems.

here are the full logs of a single connection for a freshly started server and client

edit:

after debugging a little further it seems to be a problem with my internet connection.
connecting to servers inside my LAN works flawlessly.

No matter which server I try to join (my own or something off the public list) I get disconnected after a few seconds.
Running Factorio on arch linux.
I can not move at all, but I can see trains driving + chat. Disconnect will hit me after a few seconds.

Client log:

1256.076 Info ...