Can you try setting a unique SSID for the 5ghz network and connect the panel and IQ Remote to the 2.4 network as a test? Any luck pairing? Typically there is a router component to these issues, and I am curious if the Remote and IQ Panel are not playing nicely with the two networks.
If it works, try setting the 5ghz network back to the same SSID and make sure the Remote and IQ Panel still work normally.