In case anyone cares, the issue is that the cable modem was blocking traffic because the MAC address on the ethernet interface on the new net5501 Zeroshell router was different than that on the old router.
I was able to change the MAC address via the shell to prove that was the issue. But that does not survive a power cycle.
I don’t see a way in the UI to set MAC addresses on interfaces. Am I missing it? Or, is there a start up script that I could edit to set the MAC address on boot?
I’ll also look into seeing if the net5501 has a bios setup that will change the MAC address…