Asrock J5005-itx

[agent_kith]

Damn realtek! Never tried to taint kernel before, doesn't look like a rocket since from here, but I suspect that I'll have to do it after every kernel update... Since my case has only one pci slot, which is reserved for USB regen, can I use USB wifi card? Are they even supported? 

Not too sure to be honest. Later versions of the kernel may work. But it can be hit and miss: e.g. see here.

You should be able to find a board with Intel based chipset. In my experience Intel network chips are stable, low latency and quick, see this thread.

Failing that, it may be possible for me to build 4.15.x series of kernel, with the patches to get this NIC going. Risk with this is I can only build the kernel, but cannot do much in terms of support beyond that. So if there's any issue, it may be hard for me to diagnose remotely (because if there's no network, I can't access it).