Cisco Bugs And IP Addresses

There is a rare bug with Cisco routers that is common enough to be a nuisance. The symptoms are your cable modem is online but you cannot get a valid IP address no matter what you try. The cause is a bug in the Cisco IOS. If you don't want to call Charter what you can try is leave your cable modem unplugged overnight, or for 24 hours if possible. This will give time for the DHCP servers to clear your client and your MAC address to time out of the ARP table from the Cisco router.

If that doesn't work you'll have to have a Charter tech come out so they can confirm the issue then have a Network Admin run these commands:

clear cable modem [modem MAC] delete
and
clear ip arp [Cable Modem-IP]
and
clear ip arp [CPE-IP]
and
clear cable host [CPE MAC]