I have a Dell PowerEdge 2900 Server running SBS2003 R2 premium. This server is the domain controller, the DHCP server, the Exchange server and the SQL server. An XP Pro workstation (terminal services server) sits beside it running a terminal services program WinConnect Server XP. There are 5 other workstations in the LAN connected to the server via a Lynksys switch. A Sonicwall TZ-180 router is the gateway. The Sonicwall connects to a Netgear DG834 ADSL modem/router which in turn connects to the internet with a static IP address.
Several remote clients connect to the terminal services server over the internet via remote desktop to run MS Office 2003 and an SQL accounting package called Exonet. Every hour the RDP sessions for the remote clients freeze all at the same time. In the middle of typing, letters stop appearing on the screen. 4 - 8 seconds later everything is fine again.
All the remote clients freeze at the same time. The freezes happen predictably once per hour, although not the same time every day; i.e., if the freeze occurs at 10:08 it will then occur at 11:08, 12:08, etc. The next day the freezes may occur at 42 minutes past the hour.
I don't think it is relevant but I should mention that some of the remote clients are in one office. In this office is another Sonicwall TZ-180 which acts as their gateway and DHCP. A VPN is set up between the 2 Sonicwall routers for the primary purpose of printing from the server to a local network printer at the remote office. The RDP sessions go through the VPN tunnel. But even if remote clients RDP to the WAN IP of the main site (i.e. not go through the VPN tunnel) the same problems occur. And the freezes occur at the same time for remote clients outside the remote office who don't use a VPN>
Running ping tests from a remote client to the terminal services server shows that during the freeze, the pings return "request timed out" 4 times in a row but otherwise return normally. Running ping tests from a remote client to the ISP's DNS server or to
www.google.co.nz do NOT timeout during the freeze.
I am assuming from the testing I have done that the problem originates inside my network. How do I track down what is causing the ping timeouts? The freezes are annoying to users.
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