ISA Server PPTP Site-To-Site Link Not Working

CIPortAuthority
CIPortAuthority used Ask the Experts™
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I have 2 servers running ISA Server 2004 Std on top of Windows Server 2003.  I had a working PPTP site to site VPN connection that linked the two.  Now for some reason, the connection has stopped working.  One site can connect to the other but both sites won't connect to each other at the same time.  If one site is connected and I try to get the other link up, I will get a host unreachable or modem device error message.  Can any one suggest what I can look for?  I have already tried recreating the site-to-site VPN setup in ISA Server.
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Commented:
I don't understand why you would need 2 vpn connections?
Follow the following link for instructions : http://www.isaserver.org/tutorials/Creating-VPN-ISA-Server-2006-Firewalls-Main-Branch-Office-Part1html.html
Or a Microsoft version : http://technet.microsoft.com/en-us/library/cc302474.aspx
Roshan MohammedCloud Engineering Officer

Commented:
Has there been any changes in your enviornmen recently, eg: windws updates, hardware changes etc?

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Commented:
@ptessels:
You must create a site-to-site entries in ISA server from the home site to the remote site and one from the remote site to the home site.  This creates 2 VPN links.  As per this overview from the first link you gave:
    * Create the Remote Network at the Main Office
    * Create the VPN Gateway Dial-in Account at the Main Office
    * Create the Remote Network at the Branch Office
    * Create the Network Rule at the Branch Office
    * Create the Access Rules at the Branch Office
    * Create the VPN Gateway Dial-in Account at the Branch Office
    * Activate the Site-to-Site Links

@S00007359:
There were no hardware change or patches applied.  I was working with the routing but I'm pretty sure I have backed all those changes out when I re-created the VPN links from scratch.  Apart from that, no changes that I know of have been made.

Author

Commented:
Just wanted to clarify some additional details I've found.  If I try and create a standard VPN connection in Network Connections and then click connect it will timeout.  This is on either the home or remote servers.  I can VPN in to either server fine from a WinXP SP3 machine.  Also, if I use the ISA control app and monitor PPTP connections, I see the incoming connection but there are no error messages logged in the event viewer.
Well, I recreated the whole VPN site-to-site setup on both servers from scratch for a second time and it appears to be working again.

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