On my Laptop (DELL Latitude E5530) with a completely fresh Windows 10 Enterprise installation any TCP connection gets disconnected after close to exactly 30 seconds. I noticed it first when Skype for Business lost its connection over and over again. I am able to reproduce the fault using any program that uses the network connection. E.g. PuTTy will stop to display the output of an ongoing ping after 30 seconds. Wireshark running on my machine shows several retransmissions and duplicate acks for the moment the problem occurs. The connection is then dropped. Other systems on the same network switch/network don't experience any problem.

Let me know if you want me to provide any log data or pcap traces.

  • I did some testing and made sure it only affects the Ethernet Connection (Broadcom NetExtreme 5761). When I'm using the Wireless connection everything is working correctly. – Jonas Köritz Dec 10 '15 at 14:34

Finally found the problem. Our DHCP Server sent me a wrong Gateway address.

  • I have the same problem with Win 7 - if using a dial up connection, it'll work for 30 seconds, drop the connection and won't reconnect - if I use the regular connection program, it will work, but I need to get the dial up thing to get my vpn connection to work - so how did you resolve your gateway address problem? Where did you enter that one? Thanks. – outofmind Apr 19 '16 at 23:09
  • Dies your dialup connection get disconnected completely? Or is it just not transferring any data? – Jonas Köritz Apr 20 '16 at 6:00
  • It gets disconnected, the window for redialing pops up and when I try to redial I get an error 628 or 619 (sometimes the one, sometimes the other) - when I check the netsh interface ip config show, I see that the standard gateway is set to - don't know if this is a valid setting in dialup connections - when I connect with the regular connection program (which doesn't use dial up for connecting), I have a standard gateway set to something like (a valid ip address, this is just an example) – outofmind Apr 20 '16 at 7:48
  • just as an additional note: in the modem advanced settings in device manager, I have the initialisation string AT+CGDCONT=1,"IP","web.vodafone.de" - without setting that APN here, it wouldn't connect at all - and I doubt that the standard gateway is a real problem as the connection works the first 30 seconds before it hangs up – outofmind Apr 20 '16 at 8:06

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