Modem Rebooting At Midnight

the modem is my own modem but almost every night, at midnight, it reboots. this problem started a few months ago.

it's a problem because whether i am playing my game or have it running, it loses connectivity, if i am not awake to reconnect it.

i am certain it is an xfinity issue because my modem is not programmable, so i could not have accidentally set it to reboot at midnight. also, if it was a device issue, it would occur at random times, not just at midnight.

please assist.