It's part of the DOCSIS standard. Users are not allowed to modify/update the firmware on a DOCSIS modem because that could potentially be used to unlock additio

It's part of the DOCSIS standard. Users are not allowed to modify/update the firmware on a DOCSIS modem because that could potentially be used to unlock additional speed outside of the users paid for speeds due to the way that the standard does bandwidth limiting on the modem instead of further upstream. That is why ISPs have lists of cable modems that are certified for their networks, and thus the ones allowed to connect to them as that is the list they have firmware updates for.