3rd Gen stickup cam won't connect to wifi

I have one ring doorbell that I've had for two, maybe three years now it's worked great without issues. I purchased another refurbished doorbell, and three stickup cams and they all worked great and then almost all at once, they just wouldn't reconnect to wifi. I thought ok, I'm out of warrantee and maybe they just gave up. I bought two more refurbished cams and neither will connect to wifi. I've cleared all connected devises from the wifi, changed the wifi to only 2.4, restarted the router, restarted the cameres... all go through all steps wonderfully until about 95% complete and POOF won't connect to wifi. I have not had this problem with ANY other device. I went so far as to disconnect the doorbell and try to connect one of the cameras and still no luck. Do these just fail randomly? Is there something that can be done to get them to connect? I've seen a LOT of people with this same problem and so far it seems like they've just given up. HELP!