ADSL router can ping gateway IP but not DNS or any other IP

A customer's BT Home Hub has developed a fault. Although the Internet light
is on and the router's config page shows that it is connected and has been
allocated a public IP address, it cannot access external servers.

I can ping the public IP address and the (public) default gateway, but I
cannot ping either of the DNS servers or any other server (using its IP
address, not domain name).

Another router (Netgear DG834PN) has exactly the same symptoms.

BT support are adamant that the fault lies with the Home Hub and are sending
a replacement, even though I pointed out that the fault affected another
router as well.

Does anyone have any suggestions what may *really* be wrong? Is it likely to
be a problem with the exchange and/or ISP, rather than something with the
customer's router?

On 28/05/2011 19:30, Mortimer wrote:
> A customer's BT Home Hub has developed a fault. Although the Internet
> light is on and the router's config page shows that it is connected and
> has been allocated a public IP address, it cannot access external servers.
>
> I can ping the public IP address and the (public) default gateway, but I
> cannot ping either of the DNS servers or any other server (using its IP
> address, not domain name).
>
> Another router (Netgear DG834PN) has exactly the same symptoms.
>
> BT support are adamant that the fault lies with the Home Hub and are
> sending a replacement, even though I pointed out that the fault affected
> another router as well.
>
> Does anyone have any suggestions what may *really* be wrong? Is it
> likely to be a problem with the exchange and/or ISP, rather than
> something with the customer's router?

Can't really suggest much to be honest !

My connection is fine, and works fine, but I can't ping the BT Public
DNS servers either (maybe it's disabled or something !). So don't think
that counts as a symptom.

Have you tried tracert to see if you can spot where things go wrong ?
Tracert a domain name (eg news.bbc.co.uk) as well as an IP address.

If there was a problem with the public default gateway, then there would
be loads of people with a problem. If you can ping the public default
gateway, then that would kinda rule out a physical problem between house
and public default gateway.

Have to say, if I was BT, and I didn't have lots of people ringing to
say they had a problem in the same area, then I too would suspect the
Homehub.

Mortimer writes:
> I can ping the public IP address and the (public) default gateway, but I
> cannot ping either of the DNS servers or any other server (using its IP
> address, not domain name).
>
> Another router (Netgear DG834PN) has exactly the same symptoms.

Was this testing always done on just one PC belonging to the client?
These kinds of symptoms could happen with either malware on the client,
ICS being accidentally enabled (I've seen that twice), or a weird
firewall or routing table problem etc.

"Sam" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Mortimer writes:
>> I can ping the public IP address and the (public) default gateway, but I
>> cannot ping either of the DNS servers or any other server (using its IP
>> address, not domain name).
>>
>> Another router (Netgear DG834PN) has exactly the same symptoms.
>
> Was this testing always done on just one PC belonging to the client?
> These kinds of symptoms could happen with either malware on the client,
> ICS being accidentally enabled (I've seen that twice), or a weird
> firewall or routing table problem etc.


No, I also tested on my Vista laptop, both using a wireless and a wired
connection.