have you also considered homeplug? It is a very cheap but reliable solution. It will work if both locations are on the same side of a transformer. It is cheap, easy and portable. You connect the main device to the electrical plug by your router and with a cat5 wire, you connect it to the router. You connect the other side to the electrical plug in your workshop and connect the computer or a secondary router to it. Some even have a wifi built-in. As the old laptop in my workshop has a broken wifi, I use Homeplug and connect to Internet. For best results, connect the homeplug device on an outlet connected to a circuit that does not have electric motors connected to it as it will reduce performance.
Another solution would be to install a wifi booster near your shop assuming you have wifi in the house.
Personally, I would not rely on cell service for a reliable Internet connection.