Problem connecting devices to SBG8300

I am totally not technology savvy. My problem is connecting 3 mini Blink cameras and 2 older laptops to the SBG8300. I reset the mini Blinks and they won’t recognize the 8300 unless I unplug the router for 10 seconds. Then they may or may not recognize it, and when they do I enter the wifi password. Then they disconnect a few minutes later. Same with the older laptops. I have 2 laptops, 2 phones, and smart TV that have successfully connected without problems. Any idea’s why these camera’s and older laptops don’t connect. The problem started immediately after setting up the 8300. Hopefully this makes sense.