Been there, Jim. One cheap eBay WiFi unit seemed to work but I couldn't find its address to "talk" to it to change the SSID. It was Cat-5 connected to the router and provided WiFi connection from the garden.
Eventually a sniffer found it was using 192.168.2.254 and nothing in it could be changed. It's in a box out in the workshop now.
The simple principle is that despite all standards, it's rare for one brand of wireless networking kit to play well with another brand. I've become very adept over the years at pulling cables and then fitting Cat 5 plugs on the ends.