said by nmlobo:
There is no indication a CISCO modem would solve the OP's problem or that the 6120 is to blame. The OP reports he's had problems for years. He attempted to correct it by replacing his Linksys modem (a CISCO product btw) with a new modem, it did not help. It seems his problems originate external to his modem. FYI, my moto 6120 continue to work great
But that oldass linky modem was made by linksys prior to cisco acquisition. I had the EXACT problem he describes with my 6120 and that went away with the D3 cisco[many other people also found this out]
yours works fine because your CMTS gear doesn't have compatibility issue with the moto, only certain CMTS' have this issue.