Issues with new Wi-Fi 6 bbox and Xbox One gaming

Hello everyone,
I'm having trouble connecting to a game since I got my new Wi-Fi 6 box.
Game: DayZ on Xbox One

It's already a game that isn't optimized for consoles, but now it's impossible to join any server. The game launches 1 time out of 10 and crashes after 5 minutes.
No other issues with other games, with a 20 ping on Call of Duty.

Upload speed 600, the same for download on fiber optic.

I've already tried everything:
Clearing the console cache
Uninstalling and reinstalling the game
Forwarding the recommended ports from the Bbox interface
Setting the console to a static IP

Last night I shared my connection with my mobile network and had no issues.

So it must be something with my wired network...

Could someone help me, please? I'm really at my wit's end here.

I want to emphasize that I've been having this issue for 2 days and I was able to play a week ago after already having the new box.

I don’t understand.

Thanks in advance, everyone.

Arnaud

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