1-1 NAT died

I have a Comcast Cisco DPC3941B modem that has features randomly stop working.  Today it's 1-1 NAT.  I have two WAN IP addresses mapped to two LAN IP addresses.  The outside world can ping the two LAN devices fine but they can't maintain a TCP/IP stream.  Just a few packets trickle through per minute.  The two LAN devices have the same problem reaching the outside world while 1-1 NAT is turned on for them.

There's nothing that my 'cusadmin' login can do to see what's wrong.  I called customer service but reached somebody with no technical training.  How do I get this fixed?