@Carob, do yourself and your father a favour and ditch FS9 / FS2004. Buy P3Dv5 (not 6) for around 50GBP.
I have several GoFlight units - MCP Pro, EFIS, T8, P8 , GF166 and a LGT. All nearly 20 years old and working perfectly with Windows 11.
Firstly, they must be connected to USB2 ports. USB3 are meant to be backward compatible but it can be unreliable. Modern motherboards don’t have USB2 ports but they do have USB2 headers.
I bought this from Amazon. Xiatiaosann 2 Pack 2 Port USB 2.0 Rear Panel Expansion Bracket.
It connects to USB2 Header on my mobo. Then I bought a powered USB2 hub (backward compatible USB3) should be okay. Plug your GoFlight units into the hub that’s plugged into one of the ports on the expansion bracket.
All my units work perfectly. And the scenery is transformed in P3Dv5. Get an Academic Licence. That’s fine. I hope you read this and haven’t given up.
I also use the Pollypot software which has a bit of a learning curve but is very good.