IPad/IPhone won't conx to Cisco router

My sister has a Cisco Valet M10 router, which has a primary and a guest network setup. The guest network only operates on the 2.4Ghz band. When we are there, we attempt to connect our IPad and IPhone to the network. Both devices see the network and prompt you for the password, however neither device ever connects. I have seen this issue posted in several locations online, but have never come across the definitive answer.
Do the I-devices not like the 2.4Ghz band? Or is it just due to the fact that it is a Cisco POS?
Thanks for the help!

We have not tried to reboot the router. And, could you please tell me where I would need to go on my IOS device to see the IP address?

Cool. Will give it a try. Thx!