Thanks for following up. The problem appears to be complex. The Xfinity modem works fine, but it wants to use a single SSID for both 2.4 GHz and 5 GHz bands. I guess this enables rapid band switching in the event of excessive traffic, which is supposed to useful when there are too many separate WiFi routers in a small area, as in an apartment building where many apartments can see each other's signals. To work around this, I made Xfinity give me an older model router that still allowed the bands to be split. With the 2.4 GHz band on a separate SSID, I was able to get Phillips bulbs to connect a little more reliably, but the situation was still not satisfactory. The Phillips app Wiz shows signal strength at each bulb; the weakest bulb always showed an 8 dBm weaker signal than the strongest, no matter where it was positioned. The weakest bulb read -70 dBm, which is too weak for a reliable connection. The apartment is small, less than 25 feet across, so there is no reason why the signal should be too weak at any point. I returned the Phillips bulbs, and tried the Cync bulbs again. Strangely, none of the Cync bulbs were in working order, they did not light when powered, even after quite some time. I threw the Cync bulbs out. I reinstalled the newer model Xfinity router and returned the older router to Xfinity.
I am done with smart bulbs. I may give smart outlets a shot someday, A lot of the available wireless technology is annoyingly primitive; I already have two pairs of those stupid 5 channel remote controls taped together for the lights. The Nest speaker is still useful for playing music and finding misplaced cell phones, but honestly the whole misadventure has been a disappointing and frustrating experience. Smart homes are not mature technology yet.
