Bridge mode suddenly blocked?

For the past few months I have been happily using my Netgear C3000 with my Comcast Business service. I purchased it after all the reading about how Comcast routinely flips the CG3000 (originally installed) back into router mode from bridge/modem.  Things went along smoothly, I was able to access my VPN, I was happy.  Until tonight.  I was unable to access my VPN, and after checking my logs, it appears that since December 2, my device has been operating as a router again. No problem, just change it back - except it won't.  Any attempt to disable router mode results in it going back to router mode as long as the cable is connected to it.  The device webpage even shows a strange state where neither 'yes' or 'no' radio buttons are selected on this settings page.  Unplug the cable, and out of router mode it goes.  Very NOT cool.

My question is this: Did Comcast suddenly change policy and begin blocking bridge mode on any/all devices immediately if you have a dynamic IP account?