It has taken weeks and many many hours. I have (almost) completely ignored everything else in my life like dishes, pets, family and friends. The sacrifice has finally yielded success. - To my wife, I'm sorry, and thank you! - To the world I say: Pbbbtth! I did it, and I don't care if you think it's stupid or awesome.
I have two Raspberry Pi Model 3 B+'s on my desk, each with an EDUP 600mbps WiFi adapter, power adapter, and sdcard plugged into them. They are a WiFi network cord.
If I use an ethernet cable to connect one RPi to my internet router, and another ethernet cable to connect the other RPi to a network switch in the garage...
Well it does exactly what you would expect of a long ethernet cable. The two switches are connected together. If multiple device are plugged into the switch in the garage, they get ip adresses from the internet router in the house, and connect to the internet. - Simple, functional, adds a few milliseconds to a ping, and a slight bandwidth hit. ;-)
Ok, so I can ping. Actual throughput is not great.
Normal 'N' WiFi ~19Mbps bandwidth
My WiFi Wire ~ 65Kbps bandwidth
That's so bad it makes me laugh....
My WiFi adapters are currently only using one 20Mhz channel, and the Raspberry Pi's don't have a hardware network switch in them. So bandwidth is, for now, terrible.
More testing is necessary. Now that I know how to set this up maybe I need to move it to EspressoBin's, or an RPi4 (Just released today!) :-)
I'll see if I can increase the speed and post a Edu-torial.
Ha! I found the problem! MTU on the clients MUST be set to 1446 or less. - I didn't realize that fragmenting packets would cause a 3000x slow down. Once Packet size is enforced to be small enough to prevent fragmentation I get very good speeds of 30Mpbs
Next up increasing radio bandwith from 20mhz to 80mhz. Dare I go to 160mhz?!?!? - Only time will tell.
(There are legal issues here in the US with using 160mhz outside, it interferes with like weather prediction stuff...(?) - Apparently it's possible with some WiFi equipment to use two different 80mhz bands, getting effectively 160mhz; not sure if there are two full 80mhz bands that I can use outdoors legally. - I think if you enable special power regulation and stuff that you can do it.)