Unable to connect to a server

[calebm02]

So I'm trying to connect to my friend server, and the other 4 people can get on fine. But when I join, first I don't download a map, and second when I join when other people are on, it ends up making them disconnect and reconnect, I don't even get in. When its just me and the server owner on, I can join just fine.
This is annoying and I would love to play with them. All of us are running 64 bit windows, I've tried connecting as admin, with my firewall down, restarted my computer. Nothing helped.

[sillyfly]

Did you configure port forwarding correctly on your router?
A similar thing happened to me when one player had a router that changed ports around instead of forwarding them.

[calebm02]

My friend has port forwarded it correctly. We believe this is something on my end.

[sillyfly]

Yes, I meant on your end.

[cube]

It should be enough to have port forwarding set up only on one side. Can you please post log files from both your Factorio and the server?