Are you sure you cannot connect your garage with a switch in your home trough a normal cat5e or cat6 utp cable?
There's also the option of using those ethernet over powerline adaptors, but they won't work in certain setups (it's early in my country, i cannot find the correct technical terms yet).
I personally think running your miners over a wifi connection might not be a great idear in terms of stability... But that's just my (untested) opinion.
Ethernet over power really depends on your setup, I have messed with them they worked surprisingly well as a temporary solution to get a Ethernet plug. That being said I still was not happy overall and went straight cat cable.
But a single miner should have no problem with a wireless to ethernet adapter (assuming range works). If you get from amazon you can return if does not work (most big box stores are the same). But I don't think wireless will be an issue with 1 miner assuming a good signal.