Comcast business modem blocking VPN (GRE Protocol 47)? Tags: VPN Modem Servers Networking Last response: August 13, 2011 4:08 AM in Networking Share bdubs85 August 13, 2011 4:03:10 AM I have a SBS 2008 server behind a router/firewall, in turn behind a Comcast business class modem. Everything works fine until moving to a new office building. We get a new modem and IP. I transfer all the related domains to the new IP, move all the old hardware (router, firewall, server, etc...) to the new location and set up. Everything works: IMAP, SMTP, RDP thru TS, ping, etc.....except for VPN. I get Error 691: Access denied because username and/or password is invalid on the remote access server. The settings are all correct based on the settings on the server, I can even connect to VPN from a computer within the office network. Also, i have tried different accounts on the server, and i have also tried from different physical machines at different locations, same result: Error 691. I've also ran a PPTP Ping test. The client showed the ping test as successful, however sending text to the server showed nothing on the server. An initial call to Comcast, and they say "everything's unblocked"...any ideas? am i just stuck escalating the call to a manager. More about : comcast business modem blocking vpn gre protocol bdubs85 August 13, 2011 4:08:22 AM just as a sidenote, the original business line and the 2nd business line's IP's are on somewhat of the same subnet: x.x.y.y and x.x.z.z where the x's are the same. my IP address is totally different whatsoever. Can't find your answer ? Ask ! Publish Related resources: ForumProblems connecting to VPN server behind DSL modem /router ForumWindows 7 , PPTP VPN error 807 and 800 ForumVPN error 628 ForumRemote Desktop and VPN Forumdell axim VPN sync problems ForumVPN Forumxp vpn connection problem ForumCannot make VPN through 2 routers ForumVPN with 2 XP Home Forumopinions on replacing frame network with vpn ? ForumVpn in hardware firewall ForumVPN Mysteriously Working Forumno VPN over DSL/PPPoE ForumSprint PCS w/ VPN Forumsetting up vpn and having problems. ForumRouter Setup ForumISDN modem help ForumTired of Dealing with Comcast's Netgear Gateway ForumI have a westell a90 750045 07 DSL modem and I'm adding more computers than I ha ForumVPN / RDP Help!! More resources Read discussions in other Networking categories Routers Gateways VPN LAN WAN Firewalls Cisco Netgear !