Gears 4 Co-Op campaign problems

Anybody having problems with Gears 4 Co-Op? Me and my friend are trying to play and it kicks us if we try and play together.

Hello,

I had the same issue yesterday when I was trying to assist my friend in co-op.

After troubleshooting the issue, I hinted him to check NAT type, it was blocked
therefore the cause of the issue.

He forwarded the port and the issue was gone.

P.S: Welcome aboard!

Can you give me the steps how to do that? Thanks a lot!