When I put myself in the DMZ in my local network, I can connect as first or second. But when I'm the first one, he gets the same kick for not responding. When I join second, everything is well.
There seems to be a use of undocumented ports that need to be forwarded in order to play with multiple players...
Another issue is that when hosting locally, he can not join my game over my external ip, even though I have the port forwarded in my router. Trying a different port in the config doesn't solve the issue. Hamachi works fine, except this: https://forums.factorio.com/forum/vie ... =7&t=14082 where I have to set stupidly high latency just to get over the first couple of seconds where the map is uploaded and the ping messed up.
(Been using external ip from http://myip.is)
(Yes, i know how to forward ports on my router, and I'm certain I did so correctly.)
(Yes, we quadruple-checked the ip for typos.)
(Yes, we tried turning it off and on again.
![Razz :P](./images/smilies/icon_razz.gif)