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TMG not browsing web server in LAN

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  • TMG not browsing web server in LAN

    Good evening from Belgrade, let's solve some problems.

    I'll first try to make a description of the network:
    DC1 - primary domain controller, Windows Server 2008
    WEB1 - old web server, Windows Server 2003
    WEB2 - new web server, Windows Server 2008 R2
    TMG1 - Forefront TMG 2010 server, with a few publishing rules

    OK, let's go to the problem.

    I have two publishing rules in TMG:
    RULE1 - publishing rule for
    RULE2 - publishing rule for

    WEB1, the older web server has one web site called I published it some time ago and everything worked perfectly until today.
    When I try to access from external networks, I see the following error:

    • Error Code 12206: Proxy chain loop
    • Background: The gateway has detected a proxy chain loop. This condition might indicate a configuration problem on a proxy server.
    • Date: 29.2.2012 21:53:57 [GMT]
    • Server:
    • Source: Proxy

    Strange thing about that is that I can access the web site locally from any PC, via the and it works perfectly for the internal users. The only PC that cannot access locally is TMG server.

    TMG has two interfaces, LAN has private IP address with IP address, subnet mask and primary DNS server (local one). WAN interface has public IP address, subnet mask, public default gateway, and two public DNS servers.

    I tried to access the other web server locally, from TMG server. I typed and in worked perfectly, so I figured out that the problem is only between TMG and WEB1.

    Any suggestions or hints?

    And something else, two system services on WEB1 can't be started, no matter they are set to automatic start:

    1) DHCP client
    2) WinHTTP Web Proxy Auto-Discovery Service

    Last edited by srdjan; 29th February 2012, 23:47. Reason: typo