Friends can't connect to my server

[samh785]

Hello, I recently upgraded to 0.6.5 after not playing for a month or so. My friends and I played for months on my server running 0.6.1, but now they are unable to connect to my server. I don't know what happened and I've tried everything. The proper port is open, and I just launch the server and it used to work, now it doesn't!

Any ideas? I've tried resetting router, opening other ports, etc. Nothing seems to work.

[Meems33]

You will have to post server & client logs. For starters, can they connect to a vanilla server? If not then it's a connectivity issue.