@ArrDeeGee , you could make a wall plug dongle (i.e. take an extension chord you don't want, but off the female end, expose the wires, preferably tin them).   Then connect the dongle to the wall switch as you would your in-wall wiring. Then go to an outlet near your WiFi access point and plug the switch into the wall -- DON'T flip the switch -- and now your switch is powered and at a surely strong WiFi signal. If you still have trouble connecting, it's not the WiFi strength.  FWIW, I've never needed to use a dongle like this for WiFi, though I have for a troublesome Zigbee device or two.

AFAIK, there's nothing special about Kasa's WiFi needs. I run two dozen Kasa switches all around my home on 2.4GHz along side a huge ZIgbee mesh (which also runs on the 2.4GHz).  No problems with either system.