Disconnection in multiplayer Options

[Will-ko]

I persuaded a friend to download and install both C+CGZH & Shockwave to play multiplayer.

We both configured our routers for the SWR.net port, forwarding it.
Both found each other in the lobby and made a game.
When we started, I loaded instantly and then got a disconnection menu. My friend was on the loading screen still. After a while he then loaded and the game carried on for a second before giving both of us a disconnection menu which stayed until we left.

We then tried direct connect with the same problem and then we both added ourselves to the DMZ of our routers and tried again with the same problem.

Neither of us has a firewall on our PCs and with us being in the DMZ there shouldn't be any other issues between our connection.

We have tried multiple combinations of direct connect and normal lobby with either of us hosting. We just get the same issue.

Does anyone have any idea?

Thank you