Friend and I can't connect on any Co-Op style game.

Yes, we both checked to make sure that our games on the same regions.

Perhaps ypu could both setup a static ip address and see if these help. This is usually a very quick process on your console to do once googled etc.

Thank you

Yes, both of our NAT's are open.

Hi

Thanks for bringing your problem here.

Are both your regions on the game set to the same as one could be Europe and another american etc...i know this can be an issue at times.

Thank you

Hi SkylarPortko!

This sounds like it may be an issue with one of your NAT types.

You can check your NAT type in Settings>Network Settings. You should have three options for NAT type: Strict, Moderate, and Open.

If yours or your friends NAT type is set to strict or moderate it may be affecting your ability to connect in certain games. As certain NAT types can only connect to other certain NAT types. Which may be why you can connect via another friend.

Here is more info on NAT types: https://support.xbox.com/en-PH/xbox-one/networking/nat-error-solution

If this doesn't help out please come back and I'll try to help as best as I can. Or feel free to go through the troubleshooting on support.xbox.com