modum problem

I have had the same Internet service, the same modem, the same router and all of the same devices in my house since I moved in over two years ago. Last month, one of my TVs, one of my ring cameras, and one of my smart outlets stopped working. All at the same time. When I search for the network on these devices the network does not even pop up as an option to connect to, however, at the same time the network is popping up on my phone my other TVs, my other cameras, my computer, computers, etc. It is literally just the one TV, the one camera and the one smart outlet that do not work. They do not connect to the Wi-Fi network. I reached out to my Internet service and they said everything is fine that it’s either a problem with the modem or a problem with the devices. I find it hard to believe that three different devices all failed at the same exact time which leads me to believe that it’s a modem issue. When I was doing some research, I found that some devices only can support 2 GB speed and some 5 GB speed. Could there be an issue somewhere in the modem settings that is making it so I am unable to use my Internet on these devices?