Trying to connect Gen 1 to new fiber modem

I recently got fiber, and a new modem. Cannot get the Rachio Gen 1 to recognize it.

What brand and model of router is it? What bands (frequencies) and standards (802.11b, etc ) does it support?

With a Gen1, you need to make sure that you are broadcasting a 2.4ghz wifi band. A number of new routers will use a single SSID and let the devises auto-negotiate whether to use 2.4ghz or 5ghz band, which doesn’t work very well for many IoT devices that only utilize the lower 2.4ghz band. Some, like my Orbi mesh have always worked fine, but others may require you to go into the router settings and force it to broadcast both bands with separate SSID’s.