We're both using hamachi, and have tested using a vanilla world and all is fine so it's something to do with the modpack we suspect.
When I attempt to connect I am greeted with "A fatal error has occurred, this connection has been terminated."
Attached is a list of all our mods in the modpack.
Could you post the crash report. It's located in the crash-report folder in your minecraft folder.
In reply to dwarfyassassin:
could you send the full log then? The latest.log.