lane
Veteran
You could get a powerline wifi booster, runs data down the power sockets to the garage, and wifi or ethernet in there. Thats about the cheapest option assuming you have power in the garage. Just name the network home-ext or some such where your home wifi is named home. Needs to be a slightly different name so you know you are on the nearer wifi.
More expensive is to go with a mesh system.
Done this in my house now that I am having to work at home to get a better signal upstairs. Easy and reasonably effective.