Why is my broadband speed being limited

[#1]

I was on unlimited fibre and earlier in the year was receiving speeds of 37mb. In recent months that has dropped to 30mb. I've just switched to fibre extra and was told that I would still only get speeds of 30mb. I asked why and was totally confused by the explanation given. Yesterday whilst waiting for the switch to go through I noticed that my speed increased to 37mb (I tested 10 times during the day) I assume that this was when the switch was made. Today I checked the speed again whilst waiting for email confirmation that the new contract was in force and the speed had dropped to 30mb once again. Clearly speeds of 37mb are possible on my line so I would like to know why my speed has been limited by 7mb and by whom? If anyone can answer this question in layman's terms it would be very much appreciated. Thanks Trevor

[#2]

@troggy21  Welcome to the Community forum.

First of all, why have you upgraded to Fibre Extra if you have been told that your speed will not increase? What speed will your line support? To find out put your phone number in here: https://www.broadbandchecker.btwholesale.com/#/ADSL

Now the (hopefully) simple explanation. When the service is first activated the Dynamic Line Management electronics (DLM) in your local fibre cabinet is set to an default value. This determines the maximum speed that your line can support. After a few days the DLM 'tunes' the available speed by slowly increasing/decreasing the speed until the fault level reaches a preset limit. You do not see these faults as the data is simply sent again in the background.

When you upgrade the service the DLM is reset so you have to start this process all over again.

[#3]

I switched to fibre extra because I knew that my line was capable of carrying speeds of at least upto 37mb (this used to be my normal speed). Plus earlier in the year an engineer visited and fixed a fault outside my home and came in to check my equipment and told me that my router could accept speeds of 50mb +. I was given the option to switch to fibre extra at no additional cost which I did in the hope that my speed would return to at least the 37mb that I had previously received (which it did all day Wednesday). In my mind it was worth a try and would cost me no more than I'm already paying.
I put my phone number into the link that you kindly sent and I received lots of information but I don't know which figures are relevant to my situation. VDSL observed readings are 53/12.
From your explanation of DLM I take it that my line at some stage earlier this year had its preset fault level dropped from the 37mb that I used to receive to a new level of 30mb. I don't know the ins and outs of why this should have happened and I don't really want to, I'm just after the best available speed possible. Thank you for your prompt reply Baldrick1. I'm not sure if there is anything else that I can do to improve my speed? troggy21

[#4]

How are you testing your speed? If it’s over a wireless link then you need to repeat the test using an Ethernet cable between your hub and the testing computer. Nothing else should be connected whilst you’re testing. You should be getting closer to 53/12.

[#5]

Is it any wonder why I'm confused. Talk talk just guaranteed me a minimum speed of 39.6mb as opposed to the 25mb minimum guaranteed by Plusnet. This was done online by giving them my address and phone number 😲.

[#6]

@troggy21 
I’d put money on TT not guaranteeing speed over wireless.

[#7]

Hi Baldrick1, I'm connecting direct from router via ethernet, nothing else is connected. When I use wi-fi to test the speed it's always about 4mb less.

[#8]

@troggy21 

Are you on a static IP address? Failing that I’m out of ideas but something appears to be wrong.
Hopefully a Plusnet staffer will come along soon and pick this up for you.

[#9]

Thank you for your help Baldrick1. I believe that I'm using a dynamic IP. Any further help from a 'Staffer' would be much appreciated. troggy21

[#10]

My fibre speed just dropped too. The internet connection went off for 5 minutes, and when it came back, it was noticeably slower.

One thing I have noted is that my IP Address has switched from its normal locale in NW London to Manchester.

[#11]

There seems to be more going on that is beyond our understanding. I hope your normal speed returns soon.

[#12]

Hi Trevor,

I'm really sorry that you're having speed issues. I've tested your line and the tests aren't showing the cause for this, but I can see the system's restricted it to 35mbps so I've done a DLM reset for you which should take effect in an hour. 

Based on what you've said, I suspect that this speed restriction may have been done automatically due to the line fault you've had previously and the system might not have removed this by itself once the fault was fixed. 

Let me know how your speed looks after an hour's time. 

[#13]

Hi Gandalf
Thank you very much. On Friday it was giving me speeds of 43mb for most of the afternoon 😊 and then the internet stopped for a few minutes and when it came back on it was back down to 30mb again and has stayed that way.
I've tested again just now and I'm getting 51mb which is fantastic. I'll test it again in an hour like you suggest and see if it's maintained that speed.
Thanks again for your assistance Gandalf. Trevor

[#14 · Accepted solution]

Hi Trevor,

Awesome, I'm glad to see that's improved your speed. It's probably worth keeping an eye on it and if your speed drops again, then calling out another Openreach engineer visit to investigate further might be a good way to go. 

Let me know how it goes either way.

[#15]

Hi Gandalf
Monday morning (19 hours on) and I'm still getting speeds around 51mb 😊 ... It looks like you've fixed it! Thanks again so much and if the speed does drop significantly again in the future then I'll take your advice and get an openreach engineer to check it out. 🥳🥳