Here is an xfinity support thread discussing how to set address reservation for a device. A couple posts down there is a list of steps. Try this for the W115C smart chime to make sure it isn’t having trouble with DHCP reconnecting. That is the device the VDB780B directly connects to, and then the smart chime acts as a wifi extender, connecting to your router.
Many Alarm.com cameras support onboard SD card recording, however the VDB780B video doorbell does not support onboard SD card recording. It records only to the cloud.
A list of cameras which support onboard SD recording is in the link above.