BT SmartHub vs VDSL2 modem - download speed

BT Smarthub installed on 10th Nov. 75mb down. Great.

Wanted to use my PfSense box so plugged in a recently acquired VDSL2 Openreach modem. 68mb down. Lost 7mb. Thought I would wait a week to see if it would creep up but no. Tried my Draytek 2920 router - 68mb.

Put Smarthub back on - 75mb.

Why would the Smarthub be 7mb faster than a VDSL2 modem?

Chance!

You could go to another line and get the opposite results. I have tried two modem and seen different resuults and smilarly two "identical" hubs that also gave different result.

The devices are consumer grade and whilst they will be tested to meet a minimum spec, there will be differences in the front end components which will effect how it is matched to the line and every line can vary. If the termination impedance is too low you could put additional attenuation onto the signal which will cause a loss of bandwidth.


PSU noise? Another reason ...

I do have an older VDSL2 modem I could try and different PSU.

I thought that maybe there was some new tech in the smarthub that might have taken advantage of a new technology ie G.fast. But I can't see anythwhere that this has been implemented on the smarthub.

Depending on whether you have a Huawei or ECI cabinet, the matching modem is usually the better. But not always.

I have two HG612s. Currently with a 60,000 Openreach banding on my line (dammit) for no good reason, one sync's spot on 60,000 with Max a fraction lower, (odd but common), the other in the high 57,000s with roughly the same attainable as the other. Huawei cabinet.

Now running on a ZyXel VMG1312-B10A which is duff for IPv6 but sync's on the 60,000 again, showing 7.2 or 7.3dB noise margin and attainable 66000+. Roughly in line with what you are seeing, if my cap was removed.

Tried two different ECI modems with same slower result.
Got myself a Huawei HG612 3B modem and getting pretty much same result as Homehub. So it looks like the cab is Huawei.

You can find out what cabinet make you're on by following this guide http://www.kitz.co.uk/adsl/cabinet-lookup.htm

Thanks. Yep - that confirms it Huawei.