@Black-Artist Well, a mesh is an option, but you don't really need it. You may just use a WiFi range extender placed somewhere close to upstairs where it gets good signal (it "amplifies" the WiFi signal). Or a PLC WiFi access point, which depending on your house wiring could work or not. Or just run a RJ45 upstairs from the router and place there a regular access point.

@mocelet excellent thank you so much for thr reply, I'll try a Powerline adapter or WiFi Extender, sounds like a plan. I don't know why I didn't think of them tbh, outta the game far far too long. Thanks again. 

@Black-Artist 

Like mocelet said, a network expansion device is a good choice, like range extender or powerline adapters/access points. 

The range extender and access point can connect to the main router by wired cable or wireless to boost wifi signal.

Note: Some range extender does not support access point mode. 

If the whole house is running under the same power circuit, the powerline adapters with wifi function is a good choice. Like TL-WPA7510, TL-WPA8630.