Where’s the router at? Sounds like there’s not a router involved anywhere.

On soho routers with a handful of ports, usually the ports are just switchports connected to one logical LAN interface anyway. Don’t think it’d make a difference.

This isn’t entirely related to homelab, but I had this exact problem dealing with my mATX gaming PC a few years back. Spilled a beverage on it and somehow the mobo was the only casualty. But it wasn’t that easy to find a six-gen mATX mobo for under $100. If I actually had the time for games, I’d probably use it as an excuse to upgrade everything, but I only keep it around for the occasional indie or Fallout 4 binge or Fortnite session with my son.