I'm running server 2008 R2 and about 2 weeks ago (after a power cycle) the server is suddenly dropping TCP connections. (udp connections might be dropping as well but i have no way of telling this really. My primary symptoms are that RDP sessions to the server are rejected randomly (sometimes 3 or 4 times in a row) and once connected they work for a few mins then drop and reconnect a few seconds later. Also any telnet sessions that i have originate from the server to external hosts get dropped randomly as well. The crazy thing here is that if i use IPv6 to connect to the Server with Remote Desktop I never get rejected and the connection never gets dropped. I have not really tried to use IPv6 to connect to any routers/hosts but just the fact that the IPv6 Remote Desktop connection is unaffected by these problems leads me to believe that this is IPv4 only. I've read some posts tried to disable the IPv4 checksum, IPv4 TCP checksum, IPv4 Large send, and IPv4 Large Send v2 offloads on my Broadcom adapter yet i still have the same problems. I re-enabled all of these then tried to disable TCP chimney, RSS and automatic-tuning in the netsh but this didn't work either. I've been to the dell website and upgraded the firmware of the NIC and a few other internal pieces but i'm still out of luck I've been using this server for over a year with no problems until 2-3 weeks ago. I'm not sure if it was a windows update that i installed or what but something changed on or about the same day that i turned the server off overnight. This is driving me crazy. Somebody please help. Leon leonmccalla at hotmail dot ocm

Hello Leon, This could be either a packet drop or something else as well. The best way is to take a packet capture while reporducing the issue. You can install the Network Monitor 3.4 on both machines where you feel that there is a packet drop & reproduce the issue. If you are taking the capture while doing RDP you can check the traffic for tcp port 3389. To install network monitor 3.4, please follow the link: http://www.microsoft.com/en-us/download/details.aspx?id=4865 Packet drop could also be caused due to intermediate devices. Also you can check if both machines are in the same subnet or not, are these machines physical machines or virtual machine. Also check if the NIC drivers are updated to the latest version or not. Please let me know if you need any further help on this. Regards, Shweta Shweta Katke Support Engineer | Microsoft Enterprise Platform Support - Networking |Shweta - MSFT

Hello Leon, This could be either a packet drop or something else as well. The best way is to take a packet capture while reporducing the issue. You can install the Network Monitor 3.4 on both machines where you feel that there is a packet drop & reproduce the issue. If you are taking the capture while doing RDP you can check the traffic for tcp port 3389. To install network monitor 3.4, please follow the link: http://www.microsoft.com/en-us/download/details.aspx?id=4865 Packet drop could also be caused due to intermediate devices. Also you can check if both machines are in the same subnet or not, are these machines physical machines or virtual machine. Also check if the NIC drivers are updated to the latest version or not. Please let me know if you need any further help on this. Regards, Shweta Shweta Katke Support Engineer | Microsoft Enterprise Platform Support - Networking |Shweta - MSFT

IT took me weeks to solve this problem but this is what caused all my problems. my DELL server has a management card called a DRAC that shares the single physical Ethernet interface with the rest of the machine. i don't know how dell makes this work but apparently it does. Anyway I just happened to be watching the monitor as the server rebooted and i noticed the BIOS messages displaying the DRAC IP. Since the DRAC IP and the OS IP were the same I decided to remove the DRAC IP and I have not lost a TCP session since then. I still don't know if it was a DELL firmware upgrade or windows update that initiated this erratic behavior but I can tell you that the DRAC IP was set years ago and only affected windows recently.... If your DRAC card shares the Ethernet interfaces either leave it disabled or give it a separate IP. LeonLeon <leon.mccalla at ss7hosting dot com>