Monitoring customer owned cable modem with SNMP

I have a customer owned Motorola SB6121 that I would like to monitor with SNMP (Simple Network Management Protocol). When I reboot the cable modem I am able to connect to in before it downloads its configuration from Cox. After it has downloaded the configuration I can no longer access my modem over SNMP.

I have read elsewhere on the internet that you guys have decided to block this functionality from me and I would like that functionality returned to me.