VSS1 not working with BT Infinity Business Hub 3

[stuarthatto]

VSS1 has been working just fine for many years but switched to BT Infinity on Friday and has not worked since. I have had VF resynch the VSS, resetting it several times, set up port forwarding (even though this wasnt needed previously)

VSS Serial:  1224332243

It seems to me that the MTU is the issue here. From what I can see VSS1 (maybe all VSS) doesnt allow fragmented packets. The business hub has a max MTU setting of 1492, VSS seems to only allow an MTU of 1500 bytes and ignores fragmented packets. I know traffic is being fragmented because the hub is tel;ling me it is:

IN: BLOCK [5] Fragmented packet (IP 212.183.133.179->81.136.222.41 fragment_offset=1480)

stuarts-mbp:~ stuarthatto$ nslookup 212.183.133.179

Server:192.168.0.1

Address:192.168.0.1#53

Non-authoritative answer:

179.133.183.212.in-addr.arpaname = cluster4.vap.vodafone.co.uk.

My Business hub firewall is turned OFF.

It seems that the router is rejecting the packet because the DF bit is set (do not fragment) which of course the router has to do because its max MTU is set to 1492, not 1500.

So, how do I proceed here? There is no option on the BT Business Hub to ignore DF bit and VSS doesnt do MTU path discovery and allow a lower MTU.

Any help would be VERY welcome ...

Stuart

[stuarthatto]

Actually I have no evidence the DF bit is set, but it does appear that the router is seeing fragmented packets and rejecting them.

Stuart

[Jenny]

Hi Stuart,

The serial number you’ve provided is one digit too short. Please get back to us with the full serial number and we can check things here for you.

In the mean time please try changing your router settings to ‘allow fragments’.

Thanks,

Jenny

[stuarthatto]

Thank you Jenny:

VSS Serial:  21224332243

The BT Business Hub does not have a setting to allow fragments, it has a fixed MTU of 1492 and it can be changed lower but not higher.

Stu

[Retired-Matt_B]

Hi stuarthatto,

I've checked your Sure Signal and it doesn't appear to be running on the most up to date firmware.

I've asked for the firmware to be sent to the Sure Signal, this process will be completed within 24 hours.

In the mean time, please leave the Sure Signal plugged in and do not reset it at any point.

Thanks,

Matt B

[stuarthatto]

Thanks Matt, will do.

Stu

[stuarthatto]

Its been 24 hours, still no joy

[DaveCD]

Hi stuarthatto

We're aware of some users with BT Infinity are experiencing issues, see here for more information.

Please advise what lights you're seeing as this will often indicate the fault.

DaveCD

[stuarthatto]

The only light on is the top power light which is on steady.

Thanks,

Stuart

[Ben_H]

Hi Stuart,

We're not able to send the firmware update as your device isn't connecting via the ISP. Please speak to them about the known VPN issues surrounding Sure Signal and the BT Infinity Business service. 

Many thanks, Ben