Nat issue at comcast

on 1/11/2017 our VoIP box that was ysingva public IP mapped by nat stopped working.  the usdue exudted at two of our locations with nat being used.

solution was to take nat box and put in dmz.   Long term it is apparent Comcast made a change even though they have not documented it.  if you are using nat, switch modem to bridge node and use a store bought router for nat.