WCF initialization on local network hangs for 20 secs

Question

I have WCF service using basicHttpBinding.

When client and server are on same network they initial call hangs for about 30 secs than it goes smooth.

When I do the same call from client over internet with DNS than it works nicely with no hanging.

Client and server are both console applications. Server is running windows 7 and problematic client is running Windows Server 2008. Both computers on same network are using their local security policies so there is no Domain controller.

Turning off all firewalls and antivirus did not solve my problem.

This is log from setup with boxes next to each other

09:33:05,252 [1] DEBUG ChannelFactoryManager: Created ClientChannel http://192.168.1.11:18762/DiagnosticService
09:33:05,263 [1] INFO  Program: WcfAppender.InitializeWcfAppender: 08:33:05
09:33:05,274 [1] INFO  Program: File.Copy(C:temptest.txt, O:test.txt, true): 08:33:05
09:33:05,298 [1] INFO  Program: GETTING DomainFactory.LoggingDiagnosticService.GetMonitoringLevel: 08:33:05
09:33:32,661 [1] INFO  Program: GOT DomainFactory.LoggingDiagnosticService.GetMonitoringLevel: 08:33:32
09:33:32,668 [1] INFO  Program: GETTING DomainFactory.LoggingDiagnosticService.GetMonitoringLevel: 08:33:32
09:33:32,680 [1] INFO  Program: GOT DomainFactory.LoggingDiagnosticService.GetMonitoringLevel: 08:33:32
09:33:32,693 [1] INFO  Program: File.Copy(C:temptest.txt, O:test.txt, true): 08:33:32

This is log when I hit same server over the internet from different network (no delays):

09:36:56,500 [1] DEBUG ChannelFactoryManager: Created ClientChannel http://mydomain.com:18762/DiagnosticService
09:36:56,501 [1] INFO  Program: WcfAppender.InitializeWcfAppender: 08:36:56
09:36:56,501 [1] INFO  Program: File.Copy(C:temptest.txt, O:test.txt, true): 08:36:56
09:36:56,501 [1] INFO  Program: GETTING DomainFactory.LoggingDiagnosticService.GetMonitoringLevel: 08:36:56
09:36:56,680 [1] INFO  Program: GOT DomainFactory.LoggingDiagnosticService.GetMonitoringLevel: 08:36:56
09:36:56,680 [1] INFO  Program: GETTING DomainFactory.LoggingDiagnosticService.GetMonitoringLevel: 08:36:56
09:36:56,705 [1] INFO  Program: GOT DomainFactory.LoggingDiagnosticService.GetMonitoringLevel: 08:36:56

I have also tried copying test.txt file between boxes to see if I get same connectivity issue for

Answer 1

This type of error can occure when a default proxy is defined: Disable the use of the default-proxy by adding this to your app.config

<system.net>
    <defaultProxy enabled="false" useDefaultCredentials="false">
        <proxy />
        <bypasslist />
        <module />
    </defaultProxy>
</system.net>

or use useDefaultWebProxy="false" :-) as you already said in your comment