has been working fine over the weekend but I'm scared as hell to return the Centurylink modem now in case I need a backup.
When I was setting my modem up I was constantly plugging and unplugging both modems in. I wonder if there's not any authentication per se but maybe I tripped some sort of red flag in the system that gets raised when too many modems are plugged in? Maybe as some sort of built in fraud protection? There's scant information available on people using non Centurylink modems, especially from those using modems that are not on the officially supported list so it's tough to say what fringe cases are out there.
I can't buy into the flaky modem bit 100% as the modem system logs did not show any errors and even though that doesn't mean much, the timing on when it started working again is just too weird... Another theory is that my line was disabled until Centurylink received confirmation that the original modem was received back at the warehouse.