i dont know if it helps.for my way because i dont have a wifi router i use my phone for it.
i have to disable ipv6 and set up diffrent MTU Speeds for a stable connections.
For PC:
1500
For Xbox:
1250
For PS:
1480
For Bauckup Server:
9000
its just my playarround for testing fragmented packages.
i read somewhere it can be a trouble with a OpenVPN (im not sure kvm) you have to disable on startup but i dont know where at the moment may i find it .
its said here may try other kernels help or look for a known working usb wifi or lan (Ethernet) 