It's a desktop. Got the adapter for £25 on eBay brand new factory sealed. I totally forgot about guest network

I shall try. My router is in smart connect mode but it has guest network ability.
---------- Post added at 14:33 ---------- Previous post was at 13:33 ----------
Thankfully the problematic device is hard wired to my printer so being on the same network isn't of importance. Thanks Jaymoss. I can't rep you until I whore it round some but thanks