Xbox “Server has closed the connection” only on MY console (1.6.15.1) – almost every night on sleep/save

[TF6 Phantom]

Hello,

I’m experiencing a very specific multiplayer disconnect issue on Xbox Series X (version 1.6.15.1) that I can’t solve even after trying literally everything.

Setup:

• 3 players, all on Xbox Series X with Ethernet cable
• All have Open NAT type, all ports forwarded, UPnP enabled
• Me + my girlfriend are on the exact same network
• Our common friend is the one who hosts

The problem:

• “Server has closed the connection” almost every night, especially right after sleeping/saving.
• Sometimes also when joining the server.
• Occasionally the host crashes too when I try to join.
• Happens from day 1 on our new farm (we’re now at ~40 in-game days with a lot of trying).
• My girlfriend (same network, same console, same everything) never disconnects.
• When my girlfriend and I play together on our own hosted server (without the common friend), everything is 100% stable – no disconnects at all.

What we already tried (multiple times):

• Official Multiplayer Troubleshooting Guide (all steps)
• Fully quit game after every save + reload
• Clear Alternate MAC address
• Clear persistent storage / cache
• Delete local saved data (cloud save stays)
• Full reinstall of the game
• Firewall temporarily off
• Port forwarding + UPnP + DMZ tests
• Who hosts swapped

Nothing helps. The issue only appears between me and the common friend. We have been gaming with each other for years without any problems.

Is this a known Xbox 1.6.15.1 bug? Has anyone else seen the exact situation where only one specific console on the same network keeps disconnecting while the others stay connected?

Any new workaround/fix, or should we report extra details to ConcernedApe?

Thanks in advance!