said by kb0nly:
Also other customers in this community, eight of which i have seen in person, are also getting slow speeds. The DOCSIS 2.0 modem owners are getting around .3-.5mbps downstream, the DOCSIS 3.0 users are getting around 2-3mbps thanks to channel bonding.
I even went so far as to go to a friends house and swap their RCA DCM425 with my spare SB6180, their speed jumped from .3-.5mbps up to around 2mbps. I then swapped back to their modem and their speed dropped back down to .3-.5mbps. So its easily replicated.
Based on your info and the fact that I see no problems in the pingplotter results, there must be some type of Mediacom channel bonding problem in your area.