Can't see network computers, Can't connect by name, Can connect by IP address - Works fine on another network -Major Conundrum

[imthebigchief]

I'm a computer tech. My client has finally decided to give up his dying XP laptop, and to use a newer Win 7 laptop at his office. I have done lots of networking, I have spent hours searching the net and these forums, I have tried dozens of fixes, and I'm completely stumped. I've also spent about 12 hours at my client's office, in addition to time spent at my home/shop. I can't possibly bill my client for all this time (he could buy 2 or 3 new computers), but I'm determined to fix this problem, even though I'm now working on my own time.

Background stuff:

The laptop in question is a Dell Inspiron 1564, running a fully updated version of Win 7 X64 Home Premium. This laptop has a Dell Wireless 1397 WLAN Mini-Card and a Realtek PCIe FE Family Controller, both of which have the latest drivers. The network is set to Work Network, rather than home or public. Homegroup is off.

Problem:

The laptop can't see any other computers on the network. It also can't connect to any network shares via the share name - \\SharePC\ShareName. It can, however, connect to the other computers via IP address and can connect to the shares that way. The network is a workgroup, rather than a domain. This occurs, whether it is connected via the wireless network adapter, or via the wired network adapter.

There is nothing complicated about the network or router setup. I can bring my laptop (Also Win 7 Home Premium X64) to his office and I can see all the computers on the network, even when I'm not in the same workgroup. The other computers in his office can all see the problem laptop. If I bring his laptop to my home/shop, it can immediately see my 2 computers, even though it is not in the same workgroup as my workgroup. All of which is very odd.

If it was a problem with the network at his office, then why can my laptop do what his can't? If it's a problem with the laptop, why does this only happen at his office and not also at my place?

Things I've tried:

Uninstalling and reinstalling the network adapters.
Changing the computer name.
Changing the router.
Adding a USB wireless adapter, and disabling the built in adapters.
Uninstalling all excess hidden networking devices from device manager.
Disabling IPV6 from the adapters
Flushing the DNS more than a busy toilet in a stadium.
Resetting Winsock
Running all Tweaking.com repairs.
Running SFC (totally clean)
CCleaner for temp files and the registry
Clearing the CSC cache with a Microsoft Fixit.
Editing the registry TCPIP settings in HKLM-System-CCS-TCIP-Parameters
Running TDSS Killer, Malwarebytes, and Superantispyware (all clean)
And lots more that I can't think of at the moment.

I have seen networking problems in the past where the adapter chipset and a router were not compatible (very rare), but as I said I have replaced the router and also tried a USB adapter. I suppose I could take my router to his office, since I know that it works on my network, and if that is the consensus on here, I'll try that, but I'd say that it's very much a longshot that it could happen with 2 different routers and 3 different adapters.

Unless someone can help with this, the only other thing I can think to do is to backup his stuff, and attempt to recover the system from the recovery partition, and start over from scratch, but considering all that I've tried, and the fact that it works fine at my place, I don't have much hope that will fix the problem either.

Thanks for your attention!

 

[imthebigchief]

If my customer was in a hurry for it, I'd have already taken care of it. This was one of those things that I could mess with for a while. He's still got a laptop that he has been using at his work. This is to be a replacement. The main problem with his work stuff is that he's got a server that is 10 or 12 years old - still running Server 2003. I'm about to build him a new machine that will be the server. He has been dragging his feet about spending the money, but he has finally ordered the parts, and I will be building the new machine the first part of next week. At that time, I will also completely redo his entire network setup. This laptop really doesn't need to be ready until that other work is completed. He wasn't in a hurry, so I have been taking my time and trying to figure out a confusing problem, which might give me some knowledge in the future that will let me fix a similar problem in a very short time.

 

[imthebigchief]

Someone (other than me) marked this as answered, which was OK at the time, because I finally gave up and decided to reinstall the OS from the recovery partition and re-do everything on the computer. I did that, and the networking was fine. After doing that, I began to install the client's software, and I learned what the actual problem was, so I'm posting this to help anyone else who might have this problem in the future, and this is the actual answer to the original question.

I now know that the problem occurred because of IPV6 being disabled on the computer. I was installing Sage 50 Accounting (Peachtree) on the client's computer. During the install, it asked (and highly recommended) that I disable IPV6 and use only IPV4, as it would make the program run faster. I figured it wouldn't hurt anything else that he does on that laptop, so I said OK to the prompt. This is when the computer lost the ability to see the other network computers and shares. It happened to me today, as I began installing Sage again, after the restoration of the laptop. Fortunately, I noticed the problem immediately after allowing Sage to disable it.

All I had to do was to re-enable it and the functionality returned. I wish I'd have known before I cloned his drive, formatted the drive, did all those updates, and transferred back his 80+ GB of stuff. I used the first fixit on the second row on this page:

https://support.microsoft.com/en-us/kb/929852