We found the Xfinity wifi router cannot add devices recently. The reason is that the factory settings of wifi router only support the 5Ghz wifi network. Since our smart product work with a 2.4Ghz wifi network. You have to separate dual-band into 2.4Ghz and 5Ghz.
Here are the steps to change the settings：
Go to http://10.0.0.1
Default user ID is admin password is password
In the menu on the left select Connection/Wi-Fi
Select edit on the 5GHz network
Top of the page select Disable there, then scroll down the page and save settings
After you connect the device successfully, you can enable 5Ghz network, the light bulb will work properly.