Enable bridge without ethernet connection

It’s been a very frustrating day. I’ve got devices that require 2.4 GHz. But the app would not let me enable dual band. So I bought my own router. I was able to set it up, but the speed is crawling. So I tried to log into the gateway to enable bridge mode. But I use Macs and don’t have ethernet connectivity. So then I bought a thunderbolt dock adapter, but getting a flashing orange light and it doesn’t work. Where do I go from here?