Connectivity and managing Your Comcast Business network
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PPTP VPN returning GRE error (806 & 807)

Have a Business Class Gateway set up in bridge mode, using a router running DDWRT firmware.  Router forwards incoming VPN traffic to the correct LAN address.


This setup has worked flawlessly since we started with Comcast 3 years ago.  No recent changes to the VPN server or router.


In the last week or so we can no longer complete a VPN connected into the office.  The intial connection request is sent to the VPN machine and the client side gets to the 'verifying username & password' step and then gets either MS error 806 or 807...I think both have to do with GRE being blocked or interrupted.  


I've rebooted all equipment and tested the VPN machine from the LAN and all works as it should.  I've also verified that no settings have changed in the router.  I can only point to the gateway or other Comcast equipment.  I know VPN is not purposely blocked, but is there something Comcast can check on their end to verify nothing is out of whack?

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Trusted Forum Contributor

Re: PPTP VPN returning GRE error (806 & 807)

Hello PLMC and welcome,


Please let us know which Comcast Gateway (CG) you are using?


Is your IPV6 settings in your CG enabled and correct and is your current VPN server/router able to handle IPV6?


CGs are now running a dual IPV4 and IPV6 stack and depending how your CG initializes will determine how your routing to you network equipment and applications is processed. If you can go into the CG feature settings you can see if one or both stacks are enabled.


Hope this helps you out and look forward to hearing from you.   


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