Rainbird Irrigation

Rainbird irrigation system has a plug in module that fits into the control panel outside. You are suppose to access the module remotely via pc, cellphone, tablet, etc. I can set it up by it keeps dropping the connection after a short time. I am using the new Cox router that shifts between 5ghz and 2.4ghz. Looks like the router stays at 5ghz. Rainbird says I need to switch to 2.4ghz, but I see no way of doing that on this new router. Any suggestions besides turning the module back in and manually controlling Rainbird system?