Hello tremble and welcome,
If you do not require the use of any Comcast static IP for your Cisco Meraki Server,i.e. direct remote access, etc., simply contact 8003913000 and use the Technical Option to have a technical agent log into your DPC3939B and put it in True Bridge Mode. This will disable all routing, wifi, etc. and only allow pass-through implementation.
Hope this helps you out.
HI Tremble, Our Business Service Center informed us that this issue has been addressed. Please let us know if further assistance is needed.