Laptop no longer sees other PCs on network

[mhl]

I have a network consisting of 2 XP Pro desktop PCs, an XP Pro laptop and a NAS drive for storage. They connect through a Netgear router, the laptop wirelessly. Initially everything worked fine. Lately, however, the laptop has been unable to see desktop #2 and today it can no longer see desktop #1 either - although it can still see and connect to the NAS drive and the internet.

I don't know if it is just coincidence but I had the laptop connected to a different wireless network yesterday while travelling - although the fact remains that it can see my home network OK, just not two of the devices on it. However I have also tried connecting laptop to network via RJ45 / Cat5 cable - and it still cannot see the two desktop PCs.

Windows firewall is disabled across the system.

Any suggestions how to fix things?

 

[Mr Goat]

When you say that laptop cannot 'see' the other PCs, what do you mean? Do you mean windows file sharing? Can you ping the PCs from the laptop and vice versa? Are all the devices on the same subnet?

 

[mhl]

When you say that laptop cannot 'see' the other PCs, what do you mean? Do you mean windows file sharing? Can you ping the PCs from the laptop and vice versa? Are all the devices on the same subnet?

I have a load of mapped drives from the desktop PCs and the NAS storage set up on the laptop. These (except NAS which is still OK) show in Windows Explorer as 'disconnected', and if I click on them I get an error message about them being unavailable or similar. Likewise in the opposite direction - the laptop hard drive is mapped to the two desktops, but it now appears as disconnected. Not at home at present to check the ping. All devices are on same subnet.

 

[Mr Goat]

In that case I'd do some basic ping testing first to make sure you can ping each device, from each device.

Have you got common username/password combinations on each device and are you using these to authenticate against the shares? If so, has any of the passwords changed which may be causing the problem? Are you logging onto the laptop with a different username/password that you were when you mapped the drives initially?

That's a few things for you to be going on with when you're next at home! Hope it helps!!

 

[arknor]

sometimes my desktop cant see my laptop to transfer files over simply changing the workgroup name makes all normal again so maybe try doing that.

i dont know why it keeps happening to me it does it every few days and its really annoying. windows says a reboot is needed when you change the workgroup name but in my experience thats utter rubbish because it takes effect instantly and you can see the shared folders etc as normal without a reboot.

 

[mhl]

In that case I'd do some basic ping testing first to make sure you can ping each device, from each device.

Have you got common username/password combinations on each device and are you using these to authenticate against the shares? If so, has any of the passwords changed which may be causing the problem? Are you logging onto the laptop with a different username/password that you were when you mapped the drives initially?

That's a few things for you to be going on with when you're next at home! Hope it helps!!

The laptop can ping the 2 desktops OK, and vice versa. No authentication required against shares, so password is not an issue. Logon to laptop has not changed since mapping drives.

 

[mhl]

SOLVED

Well, I finally got to the bottom of this problem - and pretty obscure it was too.

For some unknown reason, my laptop seems to require LMHOSTS for NetBIOS lookup to identify the other PCs on the network. (If you don't know what this is, you may prefer to remain in ignorance, or you can investigate http://technet.microsoft.com/en-gb/library/bb727013.aspx and scroll down to NetBIOS Name Resolution. The LMHOSTS setting is tucked away in Network Connection >> Properties >> TCP/IP >> Properties >> Advanced >> WINS). The LMHOSTS file is a simple text file which lists the IP addresses of the other devices on the network. Unfortunately, in my case, these IP addresses no longer matched the IP addresses which were allocated by my router - despite me having the router set to "address reservation", it is allocating random IP addresses. Once I edited the LMHOSTS file to match the IP addresses allocated by the router and rebooted the laptop, it can once again find all the mapped drives on the other PCs.

No idea why the laptop requires LMHOSTS and the other PCs don't. I suppose I can avoid this happening again by disabling the DHCP server function in the router and assigning fixed IP addresses to all the PCs.

 

[Mr Goat]

Glad you got it sorted mate.

That's weird about the router giving new and different ip's out to the devices even through there's reservations. If the mac address hasn't changed then not sure how that would happen, hey ho. Main thing is you're back up and running!

 

[malcolm]

Well, I finally got to the bottom of this problem - and pretty obscure it was too.

For some unknown reason, my laptop seems to require LMHOSTS for NetBIOS lookup to identify the other PCs on the network.

I have similar problems on my Laptop, but I can deselect the 'Enable LMHOSTS for Netbios, Can you?

I replaced my router recently for a Linksys Pre 'N' one, with this new one if the router is re-booted the PC's get new addresses when they are re-booted. The old one (also a Linksys) remembered the MAC addresses and former IP's after a restart. My NAS drives keep moving around and I need their IP's so I can log in. I may change them to fixed addresses just to solve this.

 

[mhl]

I have similar problems on my Laptop, but I can deselect the 'Enable LMHOSTS for Netbios, Can you?

I can deselect 'Enable LMHOSTS', but then the laptop no longer sees the desktops - it needs to use LMHOSTS and to have a valid LMHOSTS file with the correct IP addresses for the other devices.