I use the T3200M modem with a wired Optik TV and also one wire less set top. I disabled SmartSteering to get one wireless network on each frequency. My iPhone does not seem to stay connected to the 5G. I encountered no problems by just disabling it and creating a new SSID name for the 2.4G network. TV still works fine, and now my iPhone stays connected. It is the only device I connect to the 2.4G. The rest were left on the default SSID at 5G.
Thank you for the reassurance. I just disabled it and set things up the same way. Everything seems to be fine, except the WiFi link speeds on my phones seem to be lower overall with the frequencies separated than I remember them being with SmartSteering enabled. I don't feel any usage difference in the speeds though, so I'm not sure what to think of it yet.
Connectivity of Apple products to my wireless network with SmartSteering enabled was actually one of the issues I was dealing with, but now they have no problems connecting to the separate 2.4 GHz network. Hopefully this addresses my other issues as well.
I also used a simple program called WifiInfoView to view the WiFi traffic and to pick a less busy channel to use. Options, Channel Summary Mode is a convenient way to look at the data. High use close to your home can slow things down.