Hi all, my grandparents last week got Plusnet unlimited fibre broadband (VDSL2 FTTC service) after switching from Sky to save money. About 1 to 2 months ago, the broadband line became unstable and since has remained that way, even after switch from Sky to Plusnet.

The physical phone line in their house has not been touched since late 2018, and that was to correct the bodge-of-a-job state that it was in when they moved in a few years ago; long before the issues started. (When they moved in, there was junction box after junction box after junction box outside using not jelly crimps in suitable enclosures, but normal screw terminal blocks with very shady wiring!)


Plusnet identified a fault on their telephone line last week, what took openreach a couple of days to fix, However the broadband instability issue is still present.

I have since rolled back the firmware on their Draytek Vigor 2862n router to the firmware before all the issues started following upgrading the firmware to the latest about a month ago to see if it made a difference, which it did not.

The router is currently on firmware version “3.9.0_BT” with DSL/Modem code of “779517_A/B/C HW: A”.

Below is a screen shot of the latest DSL stats from the Vigor, as you can see there are lots of errors what I guess is causing the line to drop and resync about 2-4 times a day.



I of course have no idea about what brand of equipment is at the other end where the DSLAM is and what the best modem code to use for it is. I am wondering if non Vectoring firmware will work better as I have found for my 2860 (see below).



I also have Plusnet Fibre/VDSL2 service at home using a Draytek Vigor 2860 and get no errors for my DSL stats, but then again I don’t live in the remote country side like my grandparents do and am also using a non vectoring modem code as I have found in the past that gives me a higher upload speed.



Is there anyway to limit the speed that the VDSL modem of the 2862 syncs at or control advanced features like interleave depth and path mode? Anyone got any advice?


Regards: Elliott.

I don't profess to know what all the codes mean in the vdsl status pages but all I can say is that I see many more "errors" than that on my 130 and I consider my vdsl line to be very stable.

The fact that interleaving hasn't been applied and you are still on Fast path also suggests to me that the DLM is not seeing instability on the line.

Are you sure that it is the vdsl line which is unstable? What are the symptoms?

Because the WAN goes down a few times a day and each time the WAN uptime gets reset to 00:00:00.

The router system up time is not affected and remains high in value since the last reboot.

Could the UPS that the 2862 is plugged into be causing the issue?

If the router system up time is unaffected then that doesn't appear to be very likely.

As I say, I claim no expertise in this but only my experience which was that frequent WAN disconnections (caused by me fiddling with the router config and changing the master socket) resulted in DLM applying interleaving in pretty short order. I'm afraid I can't really help further. Back in the adsl days I found that the "flying lead" type of filters were not that reliable and could cause problems - have you considered looking at the master socket or whatever you have? Or was that done by Openreach?

3dB seems very low for downstream SNRM. 6dB is the normal lowest stable value (which is the target that the DSL infrastructure tunes to tunes to unless the ISP has applied any stability settings to the line.

Do you have any stats from before the line problem to compare with? - It does sound as if there is still a line issue to me. I'd not try to tune it out at your end by adjusting router settings.

I would say that the newer firmware is not worse - (3.9.1.2) it's worth going to. You can try the other modem codes as well.

You could put the line tel no into
https://www.dslchecker.bt.com/adsl/adslchecker.welcome
and see what the predictions are for the line (and the fault threshold)

The "BDCM" suggests that your cab is based on Broadcom. The chipset in the 2862 Draytek does not play well with these but it's better (not perfect) in the more recent firmware (3.8.something+)

My figures are 4dB and 6dB, with no apparent problems.