WiFi in the garage??

If you're willing to consider a professional solution that would be reliable, I'd bury conduit at least 12" underground between the 2 buildings and pull Ethernet cable.  Connect the wire in the home to your existing router and add a Wi-Fi access point to the other end in the garage.

If you have power coming from the house to the Garage, the best bet would be a Powerline extender. I use the TP-Link AV2000, One side connects to my router with an ethernet cable and is plugged intot he nearby power outlet, My other is upstairs in my secondary work space, because it has not only WiFi but 2 gigabit Ethernet ports, so I can connect  the TV and my computer both to ethernet for a kind of wired connection all the way, as well as setting up the WiFi to the same SSID/WPA keys as my router to be a mesh WiFi network, all my devices that are WiFi and mobile, can always connect to the best WiFi.