Well... this seems to be an open thread and unresolved. Seems there are a few unresolved for my issue which is similar but they are closed.
The OP here has a Cisco modem but perhaps a similar problem. Here is what I did and it is a workaround for now.
My connection has been going down several times a day, powering down the cable modem fixed it for few minutes. I found several large files in my Dropbox updates were causing this. When I throttled back the Dropbox uplink speed manually to 900k in Dropbox setup the cable modem stays on line and Dropbox finishes its upload. Apparently setting QoS in the router may fix this as well but I have not made tests on that.
I have a Motoroal SB 6141 with an apparently dated version of firmware. The SCM01 version of this box is what I have and SCM03 is apparently newer for several reasons, one being a security issue. Curious if SCM03 may render my problem solved.
I would like Cox to reflash my modem with the update to see if this makes my modem shutdowns go away. If I have to call in and 'do battle' with tech support on this I'm not inclined to. I've spent many hours troubleshooting this and its apparently a layer 2 battle at the cable modem. Again I can probably fix it "better" using layer 3 QoS at the router, but if layer 2 is broken at the modem, that would be good to know also.
Thanks in advance!
Gerry-