Unable to host co-op MP mission. Any ideas?

[istari6]

My friend and I had taken a long break from IL-2, and we're interested in returning and running a campaign together.  We're using Pat Wilson's Campaign Generator (latest version 16.0) and generating Coop missions, which I host on my PC through the IL-2 interface (no dedicated server or D-Server software).

 

The problem is that my friend can't join my mission, and we're at a loss on what to do next.  

 

Here's what happens, and what we've researched already:

 

1. I host the mission from my PC, starting a Multiplayer Coop mission.

2. He can see my server, joins, and enters the password.  Then the screen goes black for a time.

3. After a long delay he'll get a #10019 error.  Sometimes he'll get a #10 or #14 error immediately.

 

What I've done on my side:

* Port Forwarding is setup - 28000/28100.  I've hosted MP missions through this router before (years ago), and configuration settings haven't changed. So this should work.

* I do have a new PC since last time we played IL-2 running Windows 11.  I turned off Windows Defender entirely, and also tried switching Public Network to Private Network and back.  Didn't help.

 

I've looked across this forum's threads over the last two years, and found the following threads:

 

But nothing here seems to offer a solution.  Not sure where to turn next.  Any ideas from the group here?

 

Follow-up question - is there anything my friend would need to do on his side?  Turn off firewall, etc. to allow my server's data for the mission to flow through to his PC?  

[Charlo-VR]

Watching this thread, recently had the same problem and couldn’t fix it

[istari6]

So I solved the problem.  The answer was a new router.  Not sure what the issue was with the old one, it was fine for hosting DCS and other MP games.  But switching to a new Xfinity router (the local Internet provider) now allows my friend to log in and join a co-op session.  

[istari6]

Now the problem has returned.  With the new router.  I've rechecked port forwarding settings, deleted and reapplied, and still he can't join me.  Long black screen, then #10019 error.  Any further ideas?