Problem FTB Infinity Evolved - Specific user connection issue

[Atrocitas]

• What OS are you running? Windows 10
• Are you using minecraft hosting provider or a dedicated/local server not designed for minecraft? Local host server
• What version of FTB are you using? (Dont just say latest tell us the version) FTB Infinity Evolved 2.6.0 - Minecraft 1.7.10
• Did you add any mods to the server pack? No mods added
• What are your server specs? Intel I7-6700k, 32gbs RAM,
• A good detailed paragraph about the problem

2 Friends and I are attempting to have a server for ourselves to play FTB Infinity Evolved, I managed to get the server up and running, 1 friend is able to connect without issue, I have had him and myself on the server at the same time, the second friend continually runs into the issue of just being timed out without even connecting to the server, I see the following in the server command prompt:

[Server thread/INFO]: com.mojang.authlib.GameProfile@12048e6d[id=<null>,name=Cobrax94x,properties={},legacy=false] (/His IP:55423) lost connection: Disconnected

I have attempted a new server, new install of the client, sending him my client files, and his account is legit.

Any suggestions or further information needed please let me know