Originally Posted by Raze

I have not seen this reported before.
Firewalls can also cause conflicts

For joining an existing game, did the host go into the Gameplay section of the options, and enable LAN visibility? If so, you should be able to select Campaign, Join Online Game, then if required switch to LAN at the top, rather than Online.


OK, either the Firewalls of the Gameplay options corrected the issue.

I'll turn the firewalls back on and report back. I'm going to guess, though, that it was the options that made the difference.

It is working now.

Thanks much.