Using a specific application kills internet connection

I’ve been playing Microsoft Flight Simulator (fun game!), and in multiplayer my internet connection (sometimes) shuts down.
My first thought was that I’m just having issues with my ISP, but I’ve been able to replicate this behaviour with consistency now. No other application has this issue and otherwise, I have 100% connectivity.

What I see in the logs are a bunch of “ether2 link down” when this happens. I did try swapping cables and ports without any luck.
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One thing I have noticed is that apps like Discord keep working (I can hear other people but they can’t hear me).

To be honest, I’m a bit out of my depth here. Does anyone here have any idea what might be causing this or how I could debug this further?