Satellite internet comes to mind, but it's a complex issue. Last time I looked (a while ago), most satellite systems had satellite download, but upload was via a land line. However (as I suspected), things change.

Here's one company offering two-way connection, and there are probably more.

Dish Network, for example, offers phone, TV, and internet. I don't know if the internet is 2-way satellite yet, but if not, they're working on it.

If you just say the character has a "satellite hookup," that should be accurate enough to satisfy even technically-savvy readers.

Once you have any sort of internet access, setting up WiFi in a home or remote cabin is just a matter of installing equipment in the house. A real techie could probably put in amplifiers or relays to extend WiFi to areas outside the cabin (but not too far away).

I'm assuming he has electricity. If that was wired in, odds are good a phone line would have been also. If not, then maybe solar panels?

Line of sight access from the antenna to the satellite is important. I imagine some deep mountain valleys would be cut off.