Private tekkit classic server "End of stream"?

[ProjectYuni5]

I didn't see a support forum for servers so I thought this could be an appropriate place to put it. So here goes.

I made a private tekkit classic server to play on with my friend and I can connect and play, but my friend can't connect as he keeps getting an end of stream error. I've port forwarded the server and I'm using a VPN(Hamachi) since we have a Vanilla server we can both play on. But when he tries to run the server when I send him the files (for both the vanilla and tekkit classic sever(we changed the IP address don't worry)) he isn't able to connect to the servers from his own PC and I'm not able to find them. So I'm assuming it's an issue either with the server or with him computer thought we've checked security and firewall too.

Is there any help/advice for this? Any would be appreciated.