FTTC - large increase in latency (8ms > 25ms) after 4 day line fault fixed - DLM or something else?

sacove — Wed, 28 Aug 2024 09:48:13 GMT

Hello all

We have had FTTC here since 2015 (no FTTP available - WOODBRIDGE Cabinet 2).
Its always been slow (35/5) but with low latency (8ms ping to google / bbc / 8.8.8.8), which is important for some real time sound work I do.

On Friday last week, a fault developed, and the internet dropped. The hub probably got power cycled a good 10 times over the weekend from various family members 'checking if its come back'.

BT fixed the fault Tuesday, but since coming back on, latency has more than tripled.

Looking online, i have seen mentions of DLM and interleaving (i dont pretend to know any more than that!). From my understanding, DLM can kick in and enable interleaving if a line has instability, or a modem gets repeatedly power cycled. The system should readjust automatically after some unspecified time IF THE INSTABILITY IS RESORTED.

Now heres my issue - i currently have to travel into the office to do latency intensive work, which is expensive and inconvienient, so i am extremely keen to have this back asap, but if this issue is NOT DLM / interleaving, i could we be waiting for ever for it to 'reset'.

I have a HH5, ( and a currently disconnected HG612 modem - disconnected as it was an ebay purchase, and i figured 3rd party hardware might complicate BT recognizing the fault), so i cant see any way to actually test this.

Here are my HH5 stats:

1. Product name:	BT Home Hub
2. Serial number:	+068343+NQ40240314
3. Firmware version:	Software version 4.7.5.1.83.8.264 (Type A) Last updated 18/02/19
4. Board version:	BT Hub 5A
5. DSL uptime:	0 days, 23:38:08
6. Data rate:	7198 / 35000
7. Maximum data rate:	7484 / 40136
8. Noise margin:	6.0 / 6.9
9. Line attenuation:	37.7 / 26.4
10. Signal attenuation:	24.7 / 23.8
11. Data sent/received:	2.7 GB / 16.7 GB
12. Broadband username:	bthomehub@btbroadband.com
13. BT Wi-fi:	No
14. 2.4 GHz Wireless network/SSID:	BTHub5-XZHT
15. 2.4 GHz Wireless connections:	Enabled (802.11 b/g/n (up to 144 Mb/s))
16. 2.4 GHz Wireless security:	WPA2
17. 2.4 GHz Wireless channel:	Automatic (Smart Wireless)
18. 5 GHz Wireless network/SSID:	BTHub5-XZHT-5G
19. 5 GHz Wireless connections:	Enabled (802.11 a/n/ac (up to 1300 Mb/s))
20. 5 GHz Wireless security:	WPA2
21. 5 GHz Wireless channel:	Automatic (Smart Wireless)
22. Firewall:	Default
23. MAC Address:	34:8a:ae:90:22:46
24. Modulation:	G.993.2 Annex B
25. Software variant:	AA
26. Boot loader:	1.0.0

Is there any way i can confirm DLM has activated interleaving, and that i should expect it to return to normal at some point (and ideally wether thats 1 week, 1 month etc)?

I also understand that i have no ability to actually request interleaving turned off on FTTC, but perhaps (hopium) thats no longer the case?

Re: FTTC - large increase in latency (8ms > 25ms) after 4 day line fault fixed - DLM or something

sacove — Wed, 28 Aug 2024 12:10:29 GMT

Quick update - its dropped out again, so looks like an ongoing fault on the line

Re: FTTC - large increase in latency (8ms > 25ms) after 4 day line fault fixed - DLM or something

Katie_B — Thu, 29 Aug 2024 09:41:28 GMT

Hello @sacove.

Welcome back to the community.

I am sorry to hear you are still experiencing issues after a fault was fixed.

It is not possible to switch off interleaving, this is controlled by the DLM which is an automatic system that monitors your line and adjusts it continuously.

I would recommend getting back in touch so this can be investigated further.

Katie

This topic

FTTC - large increase in latency (8ms > 25ms) after 4 day line fault fixed - DLM or something else?

Re: FTTC - large increase in latency (8ms > 25ms) after 4 day line fault fixed - DLM or something

Re: FTTC - large increase in latency (8ms > 25ms) after 4 day line fault fixed - DLM or something