Setup Your Own Local MKW Server

[Vega]

Get off 5.0, use a modern version.

Apply cheats via this method - https://mkwii.com/showthread.php?tid=1138

I personally use Dolphin versions 10413 and 10886 (with DNS setup on Debian 10 editing the dhclient.conf) and can connect to dwc servers perfectly find. All i can really say is be sure your DNS settings on your Window machine is correct.

EDIT: Also use a real NAND, not the default NAND supplied by Dolphin