Connecting to the 2.4GHz band?

Hi

I have an app (for my weather station) that must connect to the 2.4GHz band on our WiFi router (XFinity router).   However, I cannot find any place where I can connect; only connects to the 5GHz band.  In the past, I have had 2x separate SSID's; one for 2.4 and one for 5GHz.  Nothing like that on my network.

How do I connect?

TIA!!!

R-