Check your manual to see if you should be cleaning the sensors as part of routine maintenance.

Why would you do this? It would increase risk of system failure by reducing component redundancy.

If you just want to be able to access the files on your desktop when you’re not using it, enable file sharing to the local network.

But the best solution would be to either buy a cheap hardware NAS, or build one from old components.

You might be better off returning the extender and replacing the router with a mesh system.

Many mesh routers sets can pair with each other over ethernet. So you would have one network, with two access points: one by the modem, the other in your house at the other end of the network cable.