Another oddball network problem...

[Inkblot]

I'm having an odd problem that I wonder if anybody has come across before - there are several things I haven't been able to try myself yet (Such as trying another router) but I thought I'd throw it into the mix in case anybody is familiar with it

One of our sites has a number of laptops (Compaq 610 with Win7 pro) in a workgroup and a Netgear DG834g v5, all of the laptops connect wirelessly and they can all browse the Internet at all times. It's not actually relevant other than as background info but all of the laptops apart from 1 (The instructor's laptop) are deepfrozen so no possibility of a virus.

Until today there were no shares on the network but I have just installed an application that requires installation from and access to a network share. As all of the laptops are deepfrozen the share was created on the instructor laptop and I then browsed to it from one of the other laptops - or rather, I tried to browse to it. Going into computer --> network revealed that each laptop could only see itself, the Netgear and a network printer that is installed. I could not see any other of the workgroup computers, I could not browse to the share or type in the UNC to it. Having spent 40 minutes checking and double checking the share options I rebooted the router and lo and behold, all of the laptops in the workgroup were suddenly visible. I then installed the application on the 1st laptop but when it came to the 2nd one I couldn't browse again....reboot router and bingo, I can see the workgroup. This went on through all 15 laptops - unable to browse the network (Even on laptops that I had already installed) until I rebooted the router after which the network was visible for a short time- maybe 5 minutes tops. However, even when the workgroup computers were not visible I stll had Internet access. Although the Netgear is only a couple of months old (As is everything else onsite) I updated it to the latest firmware which made no difference at all

In short:
Internet access at all times, regardless of whether the workgroup was visible or not
Workgroup access for 5 minutes after rebooting router - any machine can see the entire workgroup after a router reboot but refreshing after 5 minutes means I can only see the Netgear, a network printer and the laptop I am sitting at

I know there is nothing wrong with the share or share permissions (And of course it's not getting that far when I can't see the workgroup), I know there is nothing wrong with the wireless signal (Internet access at all times) and I know that restarting the router will mean I can see the entire workgroup - for a short while! It looks like the problem is either with the router (I'll get it changed ASAP) or the laptops - but all 16 of them? I don't have the option of hardwiring into the router at all times - I have 16 laptops and the Netgear has only 4 ports, one of which is used by the printer. I'm not aware of any firewall rule that saye "Allow access for 5 minutes only" and besides, I turned the firewall off temporarily early on in my investigations. The Netgear log reveals precisely zilch beyond logins, reboots and so on.

I'm sure there will turn out to be a rational explanation but at the moment I'm at a loss as to what it could be!

[Glenn]

What OS is the share on?

[Steve]

It doesn't sound like it's caching the shares . Does run > //server/share work? Try disabling the default rules for incoming/outgoing Netbios requests.

[Inkblot]

Thanks guys,

Glenn: The share is on a Compaq 610 running Win7 Pro

Steve: Nope, can't browse to the share (Or even to the network) and can't use a UNC path either in the Explorer address bar or in a CMD prompt - List of servers for this workgroup is not available. If I try either straight after a router reboot I can though! I have tried disabling the (Windows) firewall completely but it makes b*ggerall difference!

I think next step is a new router as I need to leave site in a little while, thankfully they don't actually need the application I have installed for a week or so

[pctech]

Could also try a factory before junking the router.

[Glenn]

Are all the laptops in the same 'homegroup' with the same password set?

[Technical Ben]

Hope you get it fixed! I use to do this on our home network all the time when I was back at home with the parents. Never did figure out what button it was to fix it, but after about 3 weeks I found it...  

PS, I'll be holding on to see what the actual fix is, and write it down somewhere safe this time!

[Inkblot]

Mitch: I did think of that but technically it's not our circuit so I didn't have the details for it and the guy who would have them was unavailable so that was a non-starter

Glenn: All of the laptops are in the same workgroup and are being logged on using thje same username/password - browse the network after a router reboot and all the laptops are there as are the router and printer, leave it 5 minutes though and all you can see is the router, the printer and whatever laptop you happen to be sitting at!

I did have a few minutes after I posted last and did some more troubleshooting - a ping between 2 of the laptops after a router reboot works fine but after 5 minutes I get "Reply from <My IP address>: Destination net unreachable" although a ping to the router or printer (Same subnet) still works so it looks more and more like a routing issue. The Netgear is handling DHCP on the network but maybe I'll try assigning statics instead - although it's as easy to just replace the router of course! About 30 minutes before I had to leave site I rebooted the router to do some more testing and for the 1st time the problem didn't happen - 30 minutes after I rebooted it I could still ping between laptops and run the application that I installed. I'm not suggesting that the problem is resolved, more that the randomness of the duration (I was only guessing at 5 minutes, as far as I can tell it was more a casue of 'up to 5 minutes') suggests a problem with the router.

Ah well, if I do ever get a definitive answer (Even if it's "Replace the router!" I'll be sure to post it