Happens to every computer on the network, not just one. Had a Cox tech out Monday, they verified it was the account, and NOT a local hardware issue.
We had two modems hooked up at the same time, mine continued to drop every 5m, the other did not. The second modem was provisioned to the same 300 that mine is. They hooked up a non-provisioned modem, and everything was fine, we could ping the cox local DNS Server without any issue... as soon as they move that modem over to my account and provisioned it... it started dropping every 5m just like the previous modem.
The case has been escalated to "Atlanta".