All of our cameras are running on 2.4ghz modem. The way around it is if you get a wifi extender and have the camera connect to the wifi extender.
But if you have a dual band router, log into the router using the information shown on the router label. In the network option you will see both 2.4 and 5gz options. Edit the name of the 2.4gz using 2.4 in the name and ensure it is enabled. Close the router URL. On your phone open wifi in settings, close wifi and re-open. You will see both the 2.4 and 5gz wifi options, select 2.4. Your camera will now pair with your phone.