For DOCSIS modems, they are only updatable and configurable via the ISP. When you connect and power on your cable modem, it requests a configuration file from s

For DOCSIS modems, they are only updatable and configurable via the ISP. When you connect and power on your cable modem, it requests a configuration file from someplace upstream. That config file contains the firmware version that is compatible with both the network and the modem, and if they don't match then it'll either ask upstream for a new firmware image or fail to connect to the network. Any configuration done by an end user is limited to the LAN portion of the network. WAN should be cut off entirely.