Smart Hub 2 Line Speed Changed to Variable

[Mike-B]

I've had Smart Hub 2 with Complete Wifi with a FTTC service and a rock steady 74mb/s downlink 'speed' for 4 or 5 years.

After downloading a file which took about 30 and would normally take justa few minutes, I tested the line speed.   This showed the line speed was very variable with the test dial swinging from around 20mb/s up to low the 60's mb/s,  it used to go straight to 70's a post a result at 74mb/s every time.

I test over wifi on a Dell laptop connecting on 5GHz band using the on line SpeedTest by Ookla

I've gone to BT on line and phone who just reset the Hub & finally advised a factory reset, none of which changed anything. And because the test result is above 60mb/s, they say there's nothing wrong.

OK I can accept that up to a point as the service has not failed, but what could cause the change in line speed and why can't BT diagnostic systems see this & correct it??

[chrisjp]

If you're testing speed over your WiFi then it's possible that it's your WiFi that is causing the variation in speed. You can test this by connecting your Dell laptop directly to the hub via an ethernet cable and then test your broadband speed.

[Mike-B]

Yes,  if only !!!   problem is my laptop doesn't have an ethernet port.

Whatever,  this problem has only been around for a week or so,  prior to this I've always had good 74mb/s results everytime using the same laptop.  

[VeteranISPUser]

Hi @Mike-B   Have you tried a different server with SpeedTest by Ookla. Some are very slow.

[Mike-B]

Hi VeteranISPUser,  yes I've tried that,  I checked out some that are geographically close to my location near Oxford & also set Ookla to connect automatically.      All tests gave similar results in mb/s terms but most notably all had the same test dial movement, a lower than I'm used to ping and a slow swing from 20's up to 60's and sometimes a slight fall back. 

I've now gone back to my longtime server, lomart (Maidenhead)

[ptrduffy]

If you use the Speed Test option in the MyBT app that will check the line speed independently of any WiFi issues.

but what could cause the change in line speed and why can't BT diagnostic systems see this & correct it??

Assuming this isn't just a WiFi issue (and that could be caused by a change in a neighbour's house, not just your own), then the answer is complicated:

• Your FTTC is delivered from the cabinet over a copper pair that was originally designed to carry only analogue voice signals - the fact that it can carry data signals at over 60 Mb/s is a minor miracle of modern technology, but one that is subject to a number of physical challenges
• The actual length of the copper wires from the cabinet to your house has the biggest impact (the signal degrades the further it travels), but this usually doesn't change over time
• However, your connection to the cabinet is still an electrical one, and therefore subject to the electrical characteristics of the copper wires themselves - these can change over time due to general ageing or environment changes (e.g a water ingress)
• The electrical signal is also subject to electromagnetic interference, which can come from numerous sources, including the data being transmitted on other lines in the same cabinet - you'll see this referred to as crosstalk
• All of the above mean that it is not always possible to know what data rate can be sustained on a given copper pair until we try sending data.  In answer to your question "why can't BT diagnostic systems see this & correct it?", the answer is "they do" - by adjusting the data rate to suit the line conditions.  The DSL system regularly checks the quality of the signal being received at your home and adjusts to ensure that it's within acceptable parameters.

You might argue that rather than adjusting the data rate to suit the line quality, BT (or Openreach) should change the line to deliver a specific data rate.  This isn't done because (a) physics and (b) economics (but mostly (a) tbh).

The longer-term solution is FTTP, which eliminates the electrical challenges of the cabinet-to-home link by replacing the entire thing with an optical path.

[Mike-B]

Hi @ptrduffy 

RE:  If you use the Speed Test option in the MyBT app that will check the line speed independently of any WiFi issues.

Yes I've done that,  it shows normal 74/19 'to the Hub'.   Only 'to the Device' has a slight variation,  most times the downlink is the same 74mb/s   only the uplink is sometimes slightly less,  say from 13 to 17mbs. 

But that raises more questions about what speed test app/system you can trust,  the BT App appears to give a a good result,  but thats a different result to BT Wholesale, and its different again with Ookla including that I can see the dial needle swinging about 30-60mb/s (my concern/question),   and the on-line stuff is different again.

[ptrduffy]

The MyBT app test is the only one that will check the broadband connection independently of the in-home connection - the others are always checking the speed to your PC.  It should also match up with what's shown on the Hub web page - if you point your browser at 192.168.1.254 and go to the Status page (I think - I don't have FTTC any more, so I can't fully remember where the line stats show) you'll see what data rate your line has connected at.

If your line speed is still showing 74 Mb/s to the Hub, then the most likely reason for your variable performance is the WiFi environment.  You can verify this by using an Ethernet cable as suggested by @chrisjp - I know you said your Dell doesn't have an ethernet port, but USB-to-ethernet adapters are fairly cheaply available.

You could also download a WiFi Analyser app to your phone.  That will show you what channels are in heavy use in your area, and then you could change the Hub WiFi channel setting to one that's hopefully quieter.

[Mike-B]

Hi again 

Yes I've concluded this might be a wifi anomily  ....  

I've tested again,  this time with all the ethernet system off (unpluged the only x1 ethernet cable to multiport switch) and aagain the Ookla needle swings around but MyBT test shows normal 74mb/s,  so this has to be wifi. 

I had already checked  192.168.1.254,  this looks normal/OK

It looks 100% normal and nothing changed from last time I looked

Data rate:20 Mbps / 79.999 Mbps

Maximum data rate:29.657 Mbps / 106.270 Mbps

Noise margin:12.1 / 9.2

Line attenuation:7.3 / 14.6

Signal attenuation:7.3 / 15.7

Re WiFi Analiser,  I have one already.   My neighbourhood is very quiet,  I see just a few at my Hub location,  the 2 or 3 I see are on 2.4GHz ch 6 or 11,  only one on 5GHz ch 36.    I have mine on ch1 and ch 48.     

Anyhow,  I'll keep playing,  maybe BT will run a reset & it'll get fixed.

MB