Hi
My line syncs at a solid 79/19 snr margin 7dB down 15dB up, it will run for days without dropping out either using the OR modem or a Zyxel SBG3300N. With the VDSL modem in my new 2860 I am using the 3.7.8 firmware and it doesnt matter which of the 2 modem firmwares I use (AnnexA_567517_562301 or AnnexA_566207_56101) but VDSL will drop 2-3 times a day.
This is what I see in the log when it drops

13:35:09 CHAP Login OK (PPPoA)
13:35:08 PPP Start (PPPoA)
13:35:05 ADSL_Status:[Mode=17A States=SHOWTIME UpSpeed=19999000 DownSpeed=79995000 SNR=7 Atten=12 ]
13:34:12 PPP Closed : Remote Terminating (PPPoA)

After much reading here I think I have the setup correct .. but would be good if someone could confirm
VDSL2 only, Modem(default or the 2 above) VLAN tag insertion enabled, Tag 101, prioriy 0, Always on, Load balance unticked
On WAN>>Internet access
WAN1 ADSL/VDSL PPPoE/PPPoA
Details
PPPoE/PPPoA - enabled PPP Authentication - Pap or Chap Idle timeout -1 Dynamic I/P

Anybody see anything wrong here? BTW I'm with Zen

If this looks ok any other suggestions I could try - Any Help would be appreciated

Thank-you
Nik

if the other modem works fine ... i think the dlm
https://support.zen.co.uk/kb/Knowledgebase/Fibre-Optic-Broadband-FTTC-What-is-DLM-and-how-does-it-work
must find many errors with the 2860
you can check the errors at physical connection line status

avoid turning on off your modem or plug / unplug it from phone socket

You can try the other firmware from UK download page (there are 2, adsl & vdsl) ... both are fine & each one has another 2 different modem codes ... it may be more stable for your the other firmware

Cheers for that - looking at the uk downloads page I can only see the firmware Ive got (Can I use the ADSL firmware ?) , where should I be looking for other modem codes?

Looked at the errors - had a couple of screenshots DS NE CRC 20 FECS 172 ES 1 UAS 53 US FE much higher - what should I be looking at (no uptime on these pages running on OR modem ATM to avoid re-sync problems)

Unfortunely the SBG3300N stats page doesnt seem to give these type of errors - lots of other data

It should be fine using the adsl firmware (perhaps the difference in modem code), have nothing to lose by trying (i mean once again your connection gets stable again)
If you search here in the forum are some threads about it
At the moment there are no other modem codes apart the ones in the wan>general setup>wan1> dsl modem codes
Look for the CRC errors mainly they are the ones causing issue with DLM

At the zyxel use the dslstats tool has many info about it, has a page with FEC, CRC errors and many other info
At draytek i think there are about same info with vdsl (only) firmware at management>dsl statistics page

Thank you very much - I am staying on the or modem for a few days - there was a temporary line fault last week some time and dlm reduced sync but that increased again back after 2 days so wont fiddle for a while yet

edit: found the thread on different modem codes - I ignored it initially cos I thought it referred to ADSL2+ not VDSL (as per the title "Draytek 3.7.8 VECTOR2 Firmware - works OK on ADSL2+") seems like draytek has a bit of work to do on the stability of their modem codes for vdsl.

Right after leaving it on the OR modem for a while to let the DLM calm down I have tried the 3.7.8 ADSL firmware

The Router has now been on for 142 hours and the VDSL has dropped once so is currently on 110 hours, the only stats I can see (telnet ADSL status or VDSL status - they show the same) show ZERO errors in that time!! Not sure I believe that !!

It re-synced after about 32 hours and my DS sync changed from 79999 to 80000 with Atten 12 (0.1dB) and snrM 4(0.1dB) (shown on the Online status - Physical connection page) and the max attainable rate rose to 91551264 bps. The interleave dropped from 1 to 0. The way that I interpret the attenuation and snrM figures should mean that given the units are (0.1dB) I have an attenuation of 1.2dB and a snrM of 0.4dB - surely these cant be correct. I am sure that the (0.1dB) is a red herring. I used to have a snrM of 7-8db measured by the Zyxel SBG3300N so I am assuming that the units of (0.1dB) are incorrect.

I have written a Perl script running on one of my raspberry pi's that logs all the stats I can extract and saves the info to a csv file (1440 data points per day). The snrM varies between 4 and 5 dB and the max attainable US varies a little between 28 and 27 Mps but nothing else changes at al. No Errors!!

I did ask support whether it was possible to have the seperate modem code "548006_A/B/C HW: A" loaded into the VDSL firmware version and the guy said he tried it inhouse but the modem code doesnt report the VDSL line data so the VDSL diagnostics page is blank apparently so no tone info either. During all this the actual throughput maesured using speedtest.net is a consistent 75 DS and 17 US

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ATU-R Info (hw: annex A, f/w: annex A/B/C)

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Running Mode : 17A State : SHOWTIME
DS Actual Rate : 80000000 bps US Actual Rate : 20000000 bps
DS Attainable Rate : 91551264 bps US Attainable Rate : 28054000 bps
DS Path Mode : Fast US Path Mode : Fast
DS Interleave Depth : 0 US Interleave Depth : 0
NE Current Attenuation : 12 dB Cur SNR Margin : 5 dB
DS actual PSD : 0.-2 dB US actual PSD : 10. 6 dB
NE CRC Count : 0 FE CRC Count : 0
NE ES Count : 0 FE ES Count : 0
Xdsl Reset Times : 0 Xdsl Link Times : 2
ITU Version[0] : b5004946 ITU Version[1] : 544e0000
VDSL Firmware Version : 05-04-08-00-00-06
Power Management Mode : DSL_G997_PMS_L0
Test Mode : DISABLE

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