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  1. #1
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    PC losing network connection

    I am running Windows XP Pro at work on a network and only my PC will lose it's connection to the network at almost the same time each day around 5pm (guess it's telling me to go home). The internet works, but I lose the network. I have to either reboot or chose log out and log back in. A huge time-waster.
    The only scheduled task is a backup that starts at about 11pm. The server has no restrictions on a time frame.

    What can I check to resolve this issue? It's been going on for months.

    --Ken

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  3. #2
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    at work ?
    ask your IT dept.
    lots of things could be causing it.
    too little info to help.
    ask your IT dept.

  4. #3
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    I AM the IT dept. If I didn't give enough information, then what do you need to know to help. Don't bother responding with that kind of an answer. Sounds like "ask your Mommy". Sometimes professionals need to kick out some questions that are a puzzle too.

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    Anything on event viewer that may shed some light on this? If not, will disabling and then re-enabling the network interface provide a less inconvenient way to solve the problem, until a definitive solution can be achieved?

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    Do you have a static IP? Maybe your IP is being renewed at that time daily, which likely would cause a momentary disconnect.

    Are there any server side restrictions in effect - time based connectivity perhaps?

    Try a different static IP for a couple of days to see if that helps.

    As with any intermittent network problem (no matter how consistent) try swapping ports on the switch with another that is problem free.

    Jock

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    Thanks.
    I had been using DHCP, I just switched over to using a static IP. The server has nothing time-based nor does my PC other than a backup at 11pm.
    I have disabled the connection and re-connected, that didn't help. I may need to delete my user on the network name mgmt and rebuilt it. Strange that it's so consistent with time. Seems like it's 24 hours from my last kickout. But there is nothing on my server under time mgmt that is restricted.
    I'll try the static IP and see if that helps and I'll report back.

    Thanks!

  8. #7
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    I changed from DHCP to static today, but it still kicked me off.
    I'll try changing ports on Monday....

  9. #8
    3 Star Lounger jockmullin's Avatar
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    Drat.

    That can only mean it's the dreaded happy hour virus
    Out of ideas here, sorry.

    Jock

  10. #9
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    Still lots of things to try.....

    What does ipconfig /all report when you are connected and what does it report when you are not connnected?

    Is there anyother host on the network that could be grabbing or attempting to grab the IP address which you use at 5pm each day?

    Do you have reserved IP pools on the DHCP server, and if so does the behaviour remain if you allocate an IP in that range?

    Does it occur on the weekend, when other hosts are silent?

    Does the DHCP server in the Server report any issues?

    Does the Event logs in the client machine report any issues?

    Does the Event logs in the Server report any issues?

    Do you have any firewall software on the client that could be triggered by an unrelated task at 5pm on a different machine?

    Does changing the time on the affected machine change the time of the network drop, or does that stay the same regardless of machine time?

    Please explain in more detail what "The internet works, but I lose the network" in your post #1: Do you mean you can access the internet from your machine but not network resources, or do you mean that the affected machine has no network connection at all, while other unaffected machines can browse the internet? It's not clear.

    These are just initial thoughts, but should get you at least one rung on the ladder to finding the issue.
    Last edited by Tinto Tech; 2012-07-07 at 13:17. Reason: typos
    In God we trust; all others must bring data.

    - William Edwards Deming. 1900 - 1993

  11. #10
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    Thank you! Those are great questions! I will review them on Monday.
    Regarding your question, the internet stays connected for all applications, but I lose the connection to the server for files. No other PC's are affected either.

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    Quote Originally Posted by kzkz View Post
    Regarding your question, the internet stays connected for all applications, but I lose the connection to the server for files. No other PC's are affected either.
    So, this should provide some diagnostic data already. Internet access is available, which means you have an active network connection and access to the Gateway.

    But, if at the same time, you have no access to network resources, consider network authentication, Active Directory, and account properties........

    ....the problem goes away if you log out and log back in, but: Does the problem occur if you log in on another workstation as the same user before 5pm? Does the problem occur if you log in on the affected workstation as a different user before 5pm?

    The event logs on the server may give extra data: look for authentication and security errors at 17:00.
    In God we trust; all others must bring data.

    - William Edwards Deming. 1900 - 1993

  13. #12
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    Ipconfig /all shows the exact same info before and after. It does occur on the weekend too when others are not active on the network. I haven't looked at the server side yet, but the logs for my PC have "Windows cannot obtain the domain controller for your computer network (the specified domain either does not exist or could not be contacted. Group policy aborted." Sound pretty generic. Then today "The security system detected an attempted downgrade attack for the server ____. The failure code failed authentication protocol Kerberos was 'there are currently no logon servers available to service the logon request." Not sure what that one means.
    A simple reboot always restores it though.

  14. #13
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    The ipconfig result is not surprising given you have an Internet connection during the time the issue is present.

    The event log entry (in the client workstation?) initially sounds worrying, but I don't think the work "attack" should be taken as an indication of malicious activity. From what I understand, the message simply means that Kerberos failed. As a result, your network authentication becomes invalid and you are no longer allowed to access network resources.

    Would be interesting to see what the server event logs say at this time, and also if you experience the same issue when logged into a different workstation with the same user credentials at 5pm.

    Technet has several instances of these messages, but no single root cause. One possible reason is network latency caused by heavy traffic (which you may have Monday-Friday at 5pm), but since it also occurs when no other clients are connected at weekends, that doesn't appear to be a cause. You note that there are no time based restrictions on users and that is borne out by the fact that you can reconnect upon a reboot (and hence re-authenticate). So, I think you need more diagnostic data from the server logs.
    In God we trust; all others must bring data.

    - William Edwards Deming. 1900 - 1993

  15. #14
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    Ok, I finally fixed the problem. Even had an IT guy come by and look at it and he couldn't figure it out.
    The server DHCP was assigning the range in 192.168.1.x, but my pc had it as 192.168.0.x. That was the IP that it originally had for my pc. So, apparently the server looked at available IP's in the correct range at certain intervals and shut off any that didn't fit. Been connected for 3 days straight now...a record.

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