I would try Powerline Network Adapters for internet connectivity instead of wifi ...
with any of this devices setting up an Ethernet connection to ur garage is
not out of the question
https://www.amazon.com/Powerline-Computer-Network-Adapters/b?ie=UTF8&node=1194444if your router using 2.4ghz try to switch to 5ghz if its supported on bothe side ( router and wifi adapter)
There is a lot of things what can kill , weaken your wifi signal .
- if any of your neighbor using the same frequency wifi on the same channel , that can weaken your signal ... all modern routers are multichannel, so they can switch across different channels when communicating to your devices. You tend to use whatever the router default is, but if neighboring wireless networks are also using the same channel, then you are going to encounter signal congestion.