Check that the "block Internet activity" button on the top of the router is in "active" mode, not in "standby" mode.
Unplug the AC power from the modem -- that will reset it.
Contact your ISP -- they can remotely & electrnically access the cable-modem, and will trouble-shoot, and, if necessary, will replace the modem, for free.
Answers & Comments
Check that the "block Internet activity" button on the top of the router is in "active" mode, not in "standby" mode.
Unplug the AC power from the modem -- that will reset it.
Contact your ISP -- they can remotely & electrnically access the cable-modem, and will trouble-shoot, and, if necessary, will replace the modem, for free.