What extender are you using?
did you mount it in the house or in the garage?
You're kind of in a catch 22. For more than 1 reason. Here's why.
1. Extenders by their very nature drop throughput 50%. Reason why is they have to revieve and retransmit using the same radio chip. this can be mitigated a bit using fastlane. Or by using a triband extender which reserves 1 of the 5ghz bands just for router----extender communication. but it still takes a little hit.
Plus if you daisy chain extenders (router----extender----extender), the 2nd extender is at 25% throughput of the orignial signal speed.
2. Distance. you're not at an insurmountable distance. But it is challenging. Its probably to far for just an extender in the garage. Potentially you could try placing the router in a window closest to the garage to see if eliminating a wall and getting it closer to the garage helps. Otherwise you could try an extender at the edge of the home and then another in the garage. but keep in mind your speed losses.
3. Price. by the time you add 2 extenders and factor in loss of speeds, buring a underground cable might be cheaper and more useful in the long term. Especially if you do it yourself.
does the garage have power ran off the home? without a seperate junction box? if so, you could check into a powerline adapter and see if it'd work.
or even a moca adapter (ethernet over coax)
If it was further, I'd recommend going with a point to point system like airbridge. its a bit more expensive but not super expensive if you're having to bury a long cable or are out of reach of ethernet.
