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It turns out this has been going on for awhile now and I just now found out. There are a dozen or two PCs behind a Cisco RV 120W. They are connected wirelessly.

The 120W only allows access to the following

  • host-a's IP address port 443 (these are HTTPS servers)
  • host-b's IP address port 22 (these are SSH servers)
  • host-c and d port 53 (these are DNS servers)
  • block everything else

NAT and DHCP are turned on and the LAN subnet is 192.168.1.*

However, if one of the Win7 PCs are rebooted, they cannot connect to the host-a 443. I do not know yet if they can connect to b, c, d. Perhaps the problem is with c, d and a, b are fine.

What I do know is that if a PC is connected to the unrestricted router, then connect to host-a, then connect back to the 120W... everything works fine.

Also, my contact there has heard from one of the users that if they try to connect over and over and over then it eventually works.

I will find out more details when I can but I would like to sound intelligent or even know the answer already if possible so I will post this question now with the details I have.

Edit: The error was not in the DNS lookup which might be because the 120W publishes itself as the DNS server during the DHCP lookup which means that there is a special case for DNS. The issue is not coming up anymore. It is possible that the users have been going to the HTTP page and then following a link to the HTTPS system. I am not certain of this because there was also connection problems to the host-b port 22.

I will delete this post if all stays working well.

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Whip out WireShark, something is probably getting blocked. I'm guessing that host c and d are DNS servers, which the clients use to lookup host a's IP and connect to some web service on it? –  Chris S Feb 22 '11 at 19:37
    
Correct. c and d are the DNS servers. See my edit. @Chris S –  George Bailey Feb 22 '11 at 20:01
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