Advice on diagnosing intermittent resyncs at half usual speed

Broadband Related > FTTC and FTTP Issues

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flatspyder:
Hello, I've moved into a new home and trying to diagnose inconsistent broadband speed. I've tried searching on a bunch of things but after a couple of weeks decided to post and just ask for some advice :) Most of the time the line is synced around 56Mbit down but every now and then it resyncs in the 20s.

A little while ago the modem was connected with the following stats:

--- Code: ------------------------- ATU-R Info (hw: annex A, f/w: annex A/B/C) -----------
Running Mode : 17A State : SHOWTIME
DS Actual Rate : 29690000 bps US Actual Rate : 14145000 bps
DS Attainable Rate : 29615376 bps US Attainable Rate : 13817000 bps
DS Path Mode : Fast US Path Mode : Fast
DS Interleave Depth : 1 US Interleave Depth : 1
NE Current Attenuation : 19 dB Cur SNR Margin : 5 dB
DS actual PSD : 7. 7 dB US actual PSD : 9. 2 dB
NE CRC Count : 0 FE CRC Count : 39432
NE ES Count : 0 FE ES Count : 34190
Xdsl Reset Times : 0 Xdsl Link Times : 11
ITU Version[0] : b5004946 ITU Version[1] : 544e0000
VDSL Firmware Version : 05-07-06-0D-01-07 [with Vectoring support]
Power Management Mode : DSL_G997_PMS_L0
Test Mode : DISABLE
-------------------------------- ATU-C Info ---------------------------------
Far Current Attenuation : 29 dB Far SNR Margin : 5 dB
CO ITU Version[0] : b5004244 CO ITU Version[1] : 434da48c
DSLAM CHIPSET VENDOR : < BDCM >
--- End code ---

I then rebooted the modem and it immediately resynced back in the 50s

--- Code: ------------------------- ATU-R Info (hw: annex A, f/w: annex A/B/C) -----------
Running Mode : 17A State : SHOWTIME
DS Actual Rate : 54985000 bps US Actual Rate : 12395000 bps
DS Attainable Rate : 54766804 bps US Attainable Rate : 12395000 bps
DS Path Mode : Fast US Path Mode : Fast
DS Interleave Depth : 1 US Interleave Depth : 1
NE Current Attenuation : 19 dB Cur SNR Margin : 5 dB
DS actual PSD : 7. 8 dB US actual PSD : 12. 6 dB
NE CRC Count : 0 FE CRC Count : 39432
NE ES Count : 0 FE ES Count : 34190
Xdsl Reset Times : 0 Xdsl Link Times : 1
ITU Version[0] : b5004946 ITU Version[1] : 544e0000
VDSL Firmware Version : 05-07-06-0D-01-07 [with Vectoring support]
Power Management Mode : DSL_G997_PMS_L0
Test Mode : DISABLE
-------------------------------- ATU-C Info ---------------------------------
Far Current Attenuation : 29 dB Far SNR Margin : 6 dB
CO ITU Version[0] : b5004244 CO ITU Version[1] : 434da48c
DSLAM CHIPSET VENDOR : < BDCM >
--- End code ---

I have a Vigor 130 modem and have been trying to get DSLstats running, but so far no luck getting it to login. The stats above were taken from the Vigor's telnet prompt, so I am able to access it okay.

Any guidance for how to diagnose the issue?

burakkucat:
Welcome to the Kitz forum. :)

On looking at the statistic snippets you have posted I immediately noted that you were using a Draytek modem/router and your Broadband service was provided as a G.993.2 over a metallic pathway (VDSL2). Hence I have moved this thread to a more appropriate location.

I always have great problems in fully understanding the information Draytek devices provide . . . and the Vigor 130 is no exception. That said, there certainly seems to be something peculiar happening with your circuit.

Unfortunately the Vigor 130 is not supported by DLSstats.

banger:
Any noise on the telephone line? My first instinct would be a dodgy modem, is it an ISP modem? My second instinct is noise on the line when the modem is trying to sync.

Any idea why the re=syncs are happening, is it DLM, or noise burst or line fault?

skyeci:
Just an idea. Why not get hold of a broadcom modem so you gather some evidence via dslstats etc. If you have it running 24/7 hopefully you might catch it e.g. hg612 3b
Useful to give to your ISP or a visting engineer in the future.

flatspyder:
Thanks for the welcome. I'm pretty new to all this so forgive the questions while I get up to speed.

@banger I don't use the telephone phone for phone calls. What's the best way to test for noise, just plug in a telephone and listen? The modem is not from the ISP, I stopped using the old Zyxel one I received from them as it had a nasty memory leak and failed to persist login details so every now and then it would crash and require logging in to type the details in again. I don't know what is causing the resyncs, any tips for things to track that could help diagnose?

@skyci thanks, I'll see about setting up the old Zyxel router which looks supported by DSLStats.

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