Looking for mesh setup to connect home and detatched garage

Thanks to everyone for your replies. I guess I was hoping for that elusive answer of "here's exactly what you need" that would solve everything. I had seriously thought about running an underground cable from the house to the garage because I'd really prefer a hardwired solution or purchasing a seperate Xfinity account just for the garage but looking at less costly options first.

In all honesty, I can get at least 40Mbps around 75-80% of the time with my current set up so perhaps what I should just focus on is replacing the inside router which has a known problem of randomly dropping the connection and be happy.  Oh, and to respond to CrimpOn , the 40+42 just goes to the outside of the garage, it's another 20'+ upstairs to my office, but you're right, there are several walls between the router and the office, and although the exterior is not brick, it's hardyplank.

You've been very helpful - I'll be back if I have problems with a router!