I had a thought a few days ago. We've always assumed the rationale for the CGN3 requirement for the 60+ plans was to bond more than 8 D3 channels and the benefits of that are obvious.
But I wonder if there isn't perhaps a secondary reason. The DPC3825, with its 2.4GHz-only wifi, would probably have difficulty delivering much more than 60 megabits in actual real world wifi performance. Could it be that they're also requiring the CGN3 so that people who sign up for the 60+ megabit packages have a chance of seeing the speed they are paying for over wifi?