My thought was that with a repeater I would BOOST the wi-fi signal throughout the house
I think we understand that part. What still escapes me is where the "base" WiFi signal is coming from. I am assuming that the modem in the garage is the source.
That would certainly explain the weak signals at the farthest point in the house.
What I'm not understanding is why you want to continue to use that unit's WiFi. Since you already have Ethernet working in all/most rooms, except yours, you already have a direct access to the web for any WiFi modem you can buy. That puts the signal inside the house and I'm betting it will have more than enough strength to cover all rooms without any repeaters and even in your front yard or porch for those Summer time watch-the-grass-grow experiences!
If you have
any attic crawl space, running a replacement Ethernet cable from the one you are using via the shade-tree-tech method between the jack boxes in the two rooms should be a 30 minute job.
I'm betting the current piece of cable is damaged. It could be used to pull a new cable between the two rooms, but the ease of doing that depends on how big the holes in the 2 x 4's are and how many curves/angles they used. If you are lucky
and the installers were smart, the jack boxes are almost back to back on the same wall. But by the time that is determined, it could have been done over the ceiling joists in the attic space.
All the wiring will still be concealed, of course.
I’ll pass on that free shipping fancy cost a month’s salary router.
But look at that styling!!! All your visitors would be impressed and probably start calling you a "Geek"! And, on Halloween, you can turn it upside down and put it next to the front door on the porch and scare the pranksters!!
Things would be so much easier for
me if you would just do as I say.