Intermittent problem with the internet on BT2700HGV BT Homehub

[DanGent]

Got a problem here with a computer not being able to get on the internet. A Windows XP PC connected by ethernet cable or USB to a BT2700HGV BT Homehub. Also have another XP laptop connected by Wifi. When just the XP laptop is connected its OK. Could ping router and google. Connected XP PC by USB, PC could not ping google and neither could XP laptop. Disconnected PC and then XP laptop could ping google. Connected PC by either network cable or USB (this router supports a USB connection) and the same thing happened, neither could ping google but both could ping the router.

So I plugged in my Ubuntu laptop by ethernet. Then before I could do much testing suddenly the PC and both laptops could ping google no problem. Downloaded updates for my AntiVirus software and etc. Thought the problem was somehow "fixed", then when I rebooted the XP PC, the same thing happened again. None of the computers could ping google. Disabling the XP PC's NIC (same as unplugging it) meant the Ubuntu laptop could ping google, so I was thinking it was some fault with the PC, then all of a sudden the Ubuntu laptop couldn't ping Google and the XP PC could!
Makes me think its nothing to do with the XP PC and some fault with the router?

My next step is to swap this ADSL BT Hub with a spare ADSL Netgear I've got and see what happens.

Is there something else I'm missing out on here? Is there some button that I should have ticked on the router setup page? By the way, the whole time the BT Hub says its connected to the internet and any of the comps can ping the router no problem and get a reply in less than a millisecond which makes me think all the connections are OK.

To actually post this I had to disable the PC's NIC otherwise I couldnt get on the internet on this laptop....

I'm going to leave the PC scanning for malware with MBAM, Spybot, Trend Micro House Call and Symantec Antivirus (its resident protection), but, to my knowledge, malware on this PC shouldn't stop the other laptops connecting to the internet unless its flooding the router with packets?

Any help would be much appreciated! Really strange problem I've got here I think.

Thanks,
Dan Gent

[Splash]

Are you using DHCP or static ip addresses? Is the homehub performing as a DNS server, or are you using external DNS?

[DanGent]

Hi Splash, thanks for the reply.

Using the default settings for the homehub, though I didn't actually set the router up so I'm just assuming its default settings!
Using DHCP for the IP addresses. I presume the homehub is acting as the DNS server but I'm not sure you know. It was only after writing this post and leaving that I realised I had only tried pinging www.google.com and not 216.239.59.99 to bypass DNS.

I will check that its the homehub being used for DNS and then try using openDNS or freeDNS to see if that alleviates the problem.

So do you think I can definitely rule out malware as a cause?

Thanks,
Dan Gent

[Splash]

Probably worth checking that both machines are being assigned different addresses.

[DanGent]

Genius Splash.
I hadn't even thought of that. When I look at the network again I'll check unique IP addresses are being assigned and also that I can ping from one machine to another. If that still doesn't work then I'll give them static IPs that are far apart. Being a BT homehub its private IP is an unconventional 192.168.1.254, but don't think that should make a difference.
If that still doesn't work then I'll hard reset the router back to factory settings just in case whoever set it up tried some funny stuff, not sure what they would have done but always worth a try!

Great suggestion,
Much thanks,

Dan Gent

[DanGent]

To follow up on this post (which has helped so much!)
The router is assigning unique IP addresses to each computer on the network (so DHCP is working fine).
No machines have the same MAC address (always worth a check).
The problem, as you helpfully mentioned Splash, is DNS.
Basically on the 2 laptops DNS works fine UNTIL the PC is connected to the router. Then all the computers can ping any IP address on the net but none can resolve any domain names e.g.
can't ping www.google.com but can ping 216.239.59.147

The Router is being used as the DNS server so I put the IP addresses for OpenDNS (from https://www.opendns.com/start/) into the IP settings on the PC and it resolves Google fine.
Strangely, once I did this with the PC the laptops work fine using the Router as the DNS server.

I didn't mentioned before but the PC had a malware infection (which I seemed to have removed using a combination of all the anti-malware apps I mentioned above). I know malware tends to mess up DNS to point users to their own fake websites but not sure how an infected PC would mess up other computer's DNS on the network, (Maybe flooding the DNS server? but the network shows 0% utilization in Task Manager).

For the moment, having the PC use OpenDNS seems to have solved the problem, but it would be interesting to know whats at fault here, whether the router or the PC.

Also, connecting the PC to the router by USB or ethernet the same thing happens. Using the router as the DNS server causes it and the laptops to not resolve domain names to IPs, but having the PC use OpenDNS it all works fine.

Thanks so much,
Dan Gent

[DanGent]

Spoke too soon. The internets started acting crazily again. Neither the PC nor the laptops can resolve domain names or even ping Google's IP address, for a minute none of the computers could even ping the router!

[DanGent]

Now the internet is working. Got the laptop and the PC repeatedly pinging google.com, but many time outs.....
Thinking its time to switch the router over?

[Splash]

timeouts could be many things - are you if you do

ping www.google.co.uk -t

form a couple of connected devices do you see the timeouts at the same time? If not I'd be asking questions of the ISP, if so I'd be looking to bin the router.

[DanGent]

what does the -t switch do? I had my linux laptop and the windows XP PC both pinging google thru it's .com domain name and its IP address (so 2 terminals open) running for 1000 something pings. There was only a few lost for a short period.

When you say
"form a couple of connected devices do you see the timeouts at the same time?"
Do you mean in some fancy ethernet daisy chain using connection sharing? I don't think so but I'm not sure what you mean.

It may well be the ISP, it is a BTHomeHub that had WEP for the default wifi encryption! (lucky I spotted that one while messing around with it).

Thanks,
Dan Gent

[Splash]

That was a typo from me - switch "form" for "from"

The -t switch just tells the machine to continuously run the pinh, rather than the default of 4 times.

Was the packet loss that you saw happening at the same time on both machines?

[DanGent]

Hi Splash,

Yes it was. Right after I wrote the post on this praising you for your correct advice, then both the laptop and the PC could not ping google.com (or its IP address so not a DNS problem). Then a minute or so later, internet access was fine for both computers! (I left them both pinging for best part of half an hour). Which makes me think your advice was right, and this is an unrelated problem!
I've basicaly left it with the guy and I'll ask him in a weeks time how his internet access has been. It looks like the problem must be with BT.

Thanks for the help Splash,
Dan Gent