Device connection problem

I've lost wifi connection with multiple devices: wireless printer, smart plugs

I have an XB8 gateway and have my MacBook, ipad, iphone, and Canon printer all connected. I was trying to connect a Cannon TR150 printer and it seemed confused by multiple addresses and wouldn't connect. I tried to do it manually; it saw the correct MAC address but still wouldn't connect. I tried following an on-line article about splitting the 2.4 from 5 networks and crashed the whole system. I did a reset on the Gateway and was able to get the network back on the internet with the above devices connected. However, I've lost all of my smart plugs and they won't connect now. The TR150 won't connect. I've only been able to use it with a direct cable to my MacBook. I've also been trying to connect a NetGear extender which is used to connect to my solar panel system and battery backups and I can't get that to work either. I appreciate any assistance you can give me.