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Invisible LAN

By MellyJC
Oct 17, 2012
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  1. I've been struggling for over a year with an intermittent network issues. I can't seem to identify when it happens vs not, more problematic is how to fix it quickly when it occurs. Help would be greatly appreciated.

    I bring my laptop (Win 7 OS) to work and connect via wifi to the LAN. It joins automatically and I have no problems with internet access. I can access files on the LAN IF I have the path already; ie, I had the file open yesterday, so it's showing in my "recent documents", or if I open Excel first and select the item from the drop-down, it opens just fine, so I have no doubts that I am on the LAN.

    The problem is that the other computers in the workgroup are intermittently not showing up in the LAN. When I click on "Network" today, I see my computer and "Wireless-G Router", but not the other computers that are on. This makes it difficult to browse and open new files that have been created on the other end.

    One possibility I'm considering is that the problem may be somehow created by attempts to connect to other networks. I'm rarely accessing the LAN at home, which may explain why it's rarely a problem, the other computers typically show up automatically, but I unsuccessfully tried accessing someone else's wifi yesterday and I'm having problems today.

    I have tried rebooting, I've tried ipconfig /release and /renew. It still shows me as being in the right workgroup, I just can't see the other computers, although I tried netstat and was able to ping the IP of the computer I'm trying to access.

    My knowledge of the prompt commands to refresh the network are minimal and I don't know if I'm missing something there or need some other method. Any advice on how I can get the LAN computers to show up?

    Other info: The main computer I need access to is running Windows XP. Another is Windows 7. I'm assuming this isn't relevant since neither one is showing up and the problem is more visibility than access related.

    Thanks!

    Edit: I was just informed the XP computer cannot access files on the 7 computer. This is not the first time my network issues have correlated with hers. Historically, lack of access between those two (ethernet wired desktops, not on wifi) turning off McAfee firewall on the 7 computer fixes it (I don't have access to try that right now) so I'm thinking this is is related, but I'm not sure it's the only time I have problems seeing the computers. I am not sure what is happening that the firewall keeps seemingly re-activating..I've turned it off "permanently" multiple times. I've tried calling McAfee for support around this, but rather than offering any different firewall settings they denied that their software was causing the problem even though deactivating their software fixes the problem immediately. Unfortunately I don't quite have the clout to get them to drop McAfee yet, so if there are firewall settings that would allow us to keep the network, or some more permanent way to keep the firewall from re-activating, that may be the first area to try..
     
  2. jobeard

    jobeard TS Ambassador Posts: 13,446   +324

    sounds to me as if not all systems are on the same WORKGROUP name.
    As typical with MS, the default workgroup name changed from XP(MSHOME), Vista(WORKGROUP), Win7(WORKGROUP) and that complicates your problem.

    Make sure ALL systems are using the same name.
    Then please explain why someone would document otherwise
     
  3. MellyJC

    MellyJC TS Rookie Topic Starter Posts: 51

    Yes, I've confirmed they are all on the same workgroup named for the company. None have been changed.

    Based on where you cut the quotation and the link you included I'm guessing there may be a misunderstanding of what I was trying to say. My apologies if I wasn't clear. Typically, the XP can access 7 files just fine - so long as the 7's McAfee firewall is not turned on. My first line of the "edit" paragraph was stating another symptom of the network problem, as I'm starting to suspect a link between the two. I'm hoping to play with toggling the McAfee firewall tomorrow and see if that correlates with both problems and will update accordingly. I hope that makes more sense?
     
  4. jobeard

    jobeard TS Ambassador Posts: 13,446   +324

    If you see access without McAfee active and no access with, then it is obvious I am sure.

    You need to create rules that
    • allow in/out udp ports 137,138,139 source = your subnet dest = your subnet
    • allow in/out tcp port 445 source = your subnet dest = your subnet
    if your router address is 192.168.1.1 then your subnet would be
    192.168.1.1-192.168.1.254
     
  5. MellyJC

    MellyJC TS Rookie Topic Starter Posts: 51

    Yay! That seems to have done the trick: Firewall is on but network computers are still showing up. Thank you. I tried finding rules like this before on McAfee's site without any luck and the tech support person denied it being caused by their software. I'll copy these rules for later in case they get wiped out again. I'm still not sure why/how the firewall turned itself back on, hopefully these settings are less likely to be undone.

    Thank you for your help! So glad it was a quick fix.
     
  6. jobeard

    jobeard TS Ambassador Posts: 13,446   +324

    Bravo! Glad to see you are all sorted out.
     


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