I do not know if this will work for everyone, but it worked for me and one of my buddies.
Go to to your home screen
Go to settings
Go to advanced settings
Then go to alternate mac address
and then clear it, then it will say restart and press it to restart your console. (This does not harm your console in anyway) It’s just a solid reset for it.
This was a similar connection problem on destiny, and it just worked for me and my friend.
Bump this if it works for you so other people can see it.
This helped me and my friend with actually being able to join and play together.
I gave it a try to see if it would fix the achievements not unlocking issues. No dice.
It didn’t fix my inability to load outskirts on co-op but it did fix my issue where none of my friends were showing as online, so that’s a plus.
Bumping so others can see if it works.
Tried this, got me and my friend to do it, made no difference.
nope, no change for me either