Hi all - I wanted to come back and advise what the issue was. I worked with a local electrician who troubleshoot the issue down to the retail purchased modem itself.
He said he found it strange that my parents never had an issue but I did. The only difference is I purchased my modem and they rented theirs from Cox.
I picked up a rental modem from Cox and measured the voltage on the line, nothing. I had spare unsupported modem lying around which I also used to test, 0.04 volts going back out, which was determined to be acceptable.
I'm not sure why my retail modem was kicking out so many volts but it has been sent in for a warranty replacement. I should have looked at that sooner but, hopefully this post will help someone else look at their equipment when trying to find out what may be going wrong for them if they have the same problem.