Getnet GA-524WA fail with Zen Internet

I reported this a few weeks back. Here's an update, in the hope it will
help anybody trying these in the future.

The product is:
http://www.scan.co.uk/products/getne...-4-port-switch

The router connects OK to any ADSL service, including Zen Internet.

It will not collect email from a POP3 server (any POP3 server, not just the
one operated by Zen) when conencted through a Zen ADSL connection.

But when connected to another ADSL service (I tried Demon and Plusnet) the
router collects email from a POP3 server correctly.

Zen could not understand the problem, but said that even if they were able
to find out the exact cause they would not change their systems to
accommodate the router's failings.

Scan refused to try to confirm the problem saying they did not have an
account with Zen to test, but they took the router back and refunded my
puchase cost (less postage).

--
Graham J

On Tue, 01 Mar 2011 10:51:57 +0000, Graham J engraved onto their
tombstone:

lects email from a POP3 server correctly.
>
> Zen could not understand the problem...

Nothing new there then.... face it, as an ISP they are a bucket of wank.
It's fine *when it works*, but when it won't work they don't have fuck
all squared of a clue.

IDENT piss over them from a very great height.

....
> IDENT piss over them from a very great height.

or even IDNET if you don't require the dyslexic version...

On Tue, 01 Mar 2011 10:51:57 +0000, Graham J made love to the words:

> I reported this a few weeks back. Here's an update, in the hope it will
> help anybody trying these in the future.
>
> The product is:
> http://www.scan.co.uk/products/getne...-modem-router-
adsl2plus-with-4-port-switch
>
> The router connects OK to any ADSL service, including Zen Internet.
>
> It will not collect email from a POP3 server (any POP3 server, not just
> the one operated by Zen) when conencted through a Zen ADSL connection.
>
> But when connected to another ADSL service (I tried Demon and Plusnet)
> the router collects email from a POP3 server correctly.
>
> Zen could not understand the problem, but said that even if they were
> able to find out the exact cause they would not change their systems to
> accommodate the router's failings.
>

You are aware that zen operate pop on port 995 as per this FAQ:

http://support.zen.co.uk/kb/Knowledg...rticleid=10400

Incoming mail (POP3): PORT 995

telnet mailhost.zen.co.uk 995
Trying 212.23.3.98...
Connected to mailhost.zen.co.uk.
Escape character is '^]'.
{won't go beyond this as requires TLS}

Mind you, 110 works for me too without TLS, but their FAQ seems to ignore
mentioning it......

telnet mailhost.zen.co.uk 110
Trying 212.23.3.98...
Connected to mailhost.zen.co.uk.
Escape character is '^]'.
+OK smarthost03.mail, Zen Internet POP3 Server Ready

On 01/03/2011 10:51, Graham J wrote:
> I reported this a few weeks back. Here's an update, in the hope it will
> help anybody trying these in the future.
>
> The product is:
> http://www.scan.co.uk/products/getne...-4-port-switch
>
> The router connects OK to any ADSL service, including Zen Internet.
>
> It will not collect email from a POP3 server (any POP3 server, not just the
> one operated by Zen) when conencted through a Zen ADSL connection.
>
> But when connected to another ADSL service (I tried Demon and Plusnet) the
> router collects email from a POP3 server correctly.

Out of interest did you look into MTU/RWIN tweaking as a potential
solution to the problem?
http://www.kitz.co.uk/adsl/MTU.htm

> Zen could not understand the problem, but said that even if they were able
> to find out the exact cause they would not change their systems to
> accommodate the router's failings.
>
> Scan refused to try to confirm the problem saying they did not have an
> account with Zen to test, but they took the router back and refunded my
> puchase cost (less postage).

--
|Bob Pullen Broadband Solutions for
|Support Home & Business @
|Plusnet Plc. www.plus.net
+--------------- twitter.com/plusnet ----------------

"Plusnet Support Team" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) o.uk...
> On 01/03/2011 10:51, Graham J wrote:
>> I reported this a few weeks back. Here's an update, in the hope it will
>> help anybody trying these in the future.
>>
>> The product is:
>> http://www.scan.co.uk/products/getne...-4-port-switch
>>
>> The router connects OK to any ADSL service, including Zen Internet.
>>
>> It will not collect email from a POP3 server (any POP3 server, not just
>> the
>> one operated by Zen) when conencted through a Zen ADSL connection.
>>
>> But when connected to another ADSL service (I tried Demon and Plusnet)
>> the
>> router collects email from a POP3 server correctly.
>
> Out of interest did you look into MTU/RWIN tweaking as a potential
> solution to the problem?
> http://www.kitz.co.uk/adsl/MTU.htm
>

The router was set for MTU = 1492 (working from memory). It can't be set
bigger than 1500, and there didn't seem any point in setting it smaller.
Besides, the POP3 packets are small, and unlikely tohave been fragmented.

--
Graham J

"Sultan of Usenet" <(E-Mail Removed)> wrote in message
news:ikiumg$r42$(E-Mail Removed)...
> On Tue, 01 Mar 2011 10:51:57 +0000, Graham J made love to the words:
>
>> I reported this a few weeks back. Here's an update, in the hope it will
>> help anybody trying these in the future.
>>
>> The product is:
>> http://www.scan.co.uk/products/getne...-modem-router-
> adsl2plus-with-4-port-switch
>>
>> The router connects OK to any ADSL service, including Zen Internet.
>>
>> It will not collect email from a POP3 server (any POP3 server, not just
>> the one operated by Zen) when conencted through a Zen ADSL connection.
>>
>> But when connected to another ADSL service (I tried Demon and Plusnet)
>> the router collects email from a POP3 server correctly.
>>
>> Zen could not understand the problem, but said that even if they were
>> able to find out the exact cause they would not change their systems to
>> accommodate the router's failings.
>>
>
> You are aware that zen operate pop on port 995 as per this FAQ:
>
> http://support.zen.co.uk/kb/Knowledg...rticleid=10400
>
> Incoming mail (POP3): PORT 995
>
> telnet mailhost.zen.co.uk 995
> Trying 212.23.3.98...
> Connected to mailhost.zen.co.uk.
> Escape character is '^]'.
> {won't go beyond this as requires TLS}
>
> Mind you, 110 works for me too without TLS, but their FAQ seems to ignore
> mentioning it......
>
> telnet mailhost.zen.co.uk 110
> Trying 212.23.3.98...
> Connected to mailhost.zen.co.uk.
> Escape character is '^]'.
> +OK smarthost03.mail, Zen Internet POP3 Server Ready

And other email services also no doubt use port 995 also. My point was that
**ALL*** POP3 connections failed, regardless of which POP3 server was
addressed; and that all such connections worked when the router did not
connect via Zen ADSL.

I got my colleague to set up a POP3 server, and monitor the traffic.

I used a known good router, connected to Zen ADSL, and tried telnet to his
POP3 server:

OPEN <IP address> 110
Connecting to <IP address>... [this appears very briefly]
+OK <servername> ready

My colleague saw his server:

Receive SYN
Send SYN, ACK
Receive ACK
Send +OK <servername> ready
Receive ACK

Then I used the GetNet router, connected to Zen ADSL, and tried telnet to
his POP3 server again:

OPEN <IP address> 110
Connecting to <IP address>...
...then nothing further

My colleague saw his server:

Receive SYN
Send SYN, ACK
.... after about 4 seconds it ...
Send SYN, ACK
.... then again after another 4 seconds ...
Send SYN, ACK

From this it would seem that the GetNet correctly sends the POP3 request but
never receives the SYN, ACK. The POP3 server continues to send SYN, ACK at
4-second intervals, presumably on the basis that one might have got lost.

My suspicion is that the GetNet router has a bug in its NAT implementation.
Using the GetNet router in bridge mode, with a separate ethernet router, did
work OK.

--
Graham J

On Tue, 01 Mar 2011 14:55:27 +0000, Graham J made love to the words:

> My suspicion is that the GetNet router has a bug in its NAT
> implementation. Using the GetNet router in bridge mode, with a separate
> ethernet router, did work OK.

It's not uncommon for Edimax products to have issues with NAT. I've
experienced it with DNS traffic on some older models; but then it's not
uncommon for *any* device to have issues with NAT (Draytek, Cisco etc).

Forgive me for pointing it out, but I had some reason to question your
troubleshooting ability. The reason I say this is because I read a rather
long thread where you talk of issues with Zen, whilst trying to telnet
against 123-reg servers. You also speak of 'pinging' the pop host, but as
ICMP is not port centric it would be largely irrelevant. ZEN have a smart
host/gateway (read plural here) in front of their core servers that offer
multiple services listening on different ports. However, it could still
happily reply to a ping with no ports open and no services listening.

Also, you story appears to shift a bit. One minute you seem to be saying
the Edimax device won't work with POP at all, the next you say it will
work with some providers but not ZEN, which is somewhat confusing to a
reader trying to follow what you've actually done.

Naturally it's all academic as you've returned the device - but I do
wonder how much of this was a layer 8 issue.

"Sultan of Usenet" <(E-Mail Removed)> wrote in message
news:ikjhb2$n9s$(E-Mail Removed)...
> On Tue, 01 Mar 2011 14:55:27 +0000, Graham J made love to the words:
>
>> My suspicion is that the GetNet router has a bug in its NAT
>> implementation. Using the GetNet router in bridge mode, with a separate
>> ethernet router, did work OK.
>
> It's not uncommon for Edimax products to have issues with NAT. I've
> experienced it with DNS traffic on some older models; but then it's not
> uncommon for *any* device to have issues with NAT (Draytek, Cisco etc).
>
> Forgive me for pointing it out, but I had some reason to question your
> troubleshooting ability. The reason I say this is because I read a rather
> long thread where you talk of issues with Zen, whilst trying to telnet
> against 123-reg servers. You also speak of 'pinging' the pop host, but as
> ICMP is not port centric it would be largely irrelevant. ZEN have a smart
> host/gateway (read plural here) in front of their core servers that offer
> multiple services listening on different ports. However, it could still
> happily reply to a ping with no ports open and no services listening.
>
> Also, you story appears to shift a bit. One minute you seem to be saying
> the Edimax device won't work with POP at all, the next you say it will
> work with some providers but not ZEN, which is somewhat confusing to a
> reader trying to follow what you've actually done.
>
> Naturally it's all academic as you've returned the device - but I do
> wonder how much of this was a layer 8 issue.

I have tried to summarise the symptoms and I apologise that in trying to be
brief I have caused confusion.

The GetNet router works when connected to an ADSL service from Plusnet or
Demon. It will download email from many different POP3 servers - I tried
about ten - including servers provided by Demon, Zen, 123-reg, and Tollon.

However when the GetNet router is connected to a Zen ADSL service it browses
web pages ok but does not download email from ***any*** POP3 server that
I've tried. The story doesn't shift - these symptoms are entirely
repeatable. I use the same computer with the same email accounts for both
tests - the only change is the ADSL service that the router connects to.

By comparison if I try the same tests with another router (Vigor, or an old
Edimax AR-7084A) then I can swap ADSL connections between Zen, Demon, and
Plusnet; and can download emails from the same set of POP3 servers without
issues.

--
Graham J

On Tue, 01 Mar 2011 23:07:35 +0000, Graham J made love to the words:

>
> However when the GetNet router is connected to a Zen ADSL service it
> browses web pages ok but does not download email from ***any*** POP3
> server that I've tried. The story doesn't shift - these symptoms are
> entirely repeatable. I use the same computer with the same email
> accounts for both tests - the only change is the ADSL service that the
> router connects to.
>

Thing is, you said the vendor could not reproduce your issue as they did
not have a Zen account? If it is every POP server out their then they
would be able to recreate the issue against their own provider if *no*
pop service will work.

Whilst I understand your feelings about NAT being guilty, and they have
issues like any other, I'm not sure I buy it based on your
troubleshooting. Personally I would have done shed loads more testing
across other ports myself, along with multiple connections to the same
port.

Still, it's gone back now - let's wait for google to fill with news of
how it does not work with POP3 servers.........