Current stats:

Code:

> vdsl status ---------------------- ATU-R Info (hw: annex A, f/w: annex A/B/C) ----------- Running Mode : 17A State : SHOWTIME DS Actual Rate : 66996000 bps US Actual Rate : 20000000 bps DS Attainable Rate : 79180944 bps US Attainable Rate : 23922300 bps DS Path Mode : Fast US Path Mode : Fast DS Interleave Depth : 0 US Interleave Depth : 0 NE Current Attenuation : 15 dB Cur SNR Margin : 7 dB DS actual PSD : 6. 0 dB US actual PSD : 6. 0 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] : 00000000 ITU Version[1] : 00000000 VDSL Firmware Version : 05-04-08-00-00-06 Power Management Mode : DSL_G997_PMS_L0 Test Mode : DISABLE -------------------------------- ATU-C Info --------------------------------- Far Current Attenuation : 0 dB Far SNR Margin : 7 dB CO ITU Version[0] : b5004946 CO ITU Version[1] : 544eb206 DSLAM CHIPSET VENDOR : < IFTN >

Apologies for resurrecting this old thread of mine, but I'd be grateful for peoples opinions.

After having had long periods of line stability with lower sync speeds of 20000/67000:
- about 45 days using 3.8.4_std and 3.8.4_std
- about 30 days using 3.8.4.2_bt (change of firmware suggested by Draytek support)
I thought I'd try and get BT to sort out the lower sync setting on the line. After checking things remotely they arranged for an engineer to monitor the line for 48 hrs during which time, by checking the DSL status, I could see the attainable rates improving. After 48hrs the line was reset and it was syncing at 20000/79995 again. That was 2 days ago, but this morning the line dropped and reconnected at 15282/54086, in fact looking at the stats now, the attainable rate is now lower than the actual rate.

Code:

vdsl stat ---------------------- ATU-R Info (hw: annex A, f/w: annex A/B/C) ----------- Running Mode : 17A State : SHOWTIME DS Actual Rate : 53960000 bps US Actual Rate : 15150000 bps DS Attainable Rate : 53636264 bps US Attainable Rate : 15121746 bps DS Path Mode : Fast US Path Mode : Fast DS Interleave Depth : 1 US Interleave Depth : 1 NE Current Attenuation : 24 dB Cur SNR Margin : 5 dB DS actual PSD : 6. 7 dB US actual PSD : 6. 8 dB NE CRC Count : 507 FE CRC Count : 2150 NE ES Count : 142 FE ES Count : 1737 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 : 24 dB Far SNR Margin : 6 dB CO ITU Version[0] : b5004946 CO ITU Version[1] : 544eb206 DSLAM CHIPSET VENDOR : < IFTN >

It seems to me that the router can reliably hold a connection at the lower sync speeds but not the higher sync speeds.
Why would that be?
Grateful for your views.

I know that they all recommend the BT version but there is stuff going on underneath that nobody is letting on about. Don't know what it is (because nobody is letting on about it!!) but here are the conclusions I came to (and so have some other people I think): -

The BT version may work properly on many lines but if you have a situation where it keeps disconnecting (a lot, like every few minutes or more than twice a day) and so knocks the speed then you may need to try other versions. It looks like with some cabinets the BT version causes re-syncs all the time. For me (the three VDSL lines I control in Essex)...

• BT version keeps disconnecting every few minutes at times


• The 'std' version is stable but always at a lower rate


• The VT3 & VT2 versions act the same as the BT version


• The VT1 version with modem code 566207 selected produces a permanently stable full speed connection (once it recovers from the knock caused by all the disconnects) on lines which do not have other quality issues

Thanks for your reply jedi98 (and all of your previous help on this matter).
For the time being I've totally given up on the Draytek modem (and to a degree, Draytek themselves for their lack of openness on this matter) and have reconnected the Openreach modem on Wan2. I'm in the process of getting BT to reset my line (again!) and I'll leave it like that for a while hoping for a period of stability. Kind of annoying since I bought the Draytek to replace the BT Hub and separate modem for the one unit.
I'll monitor this forum and future firmware release notes and might try again in 6 months or so if things look a bit more promising.

I came to this forum to ask a question about the 2860 experiencing line drops on a Plusnet (BT) FTTC line, but I see it's a wider problem...
What I see from the logs is that the 2860 connects at (say) 6dB SNR down, but then at some point this will reduce to 0dB, at which point the modem disconnects and re-syncs. After the re-sync, th SNR will be back up to 6 or 7 dB again, and the whole process repeats.
If I set the SNR margin higher, it will remain connected for longer but at a slower rate, but it will still eventually fall to 0dB and re-sync, conversely, if I set the SNR margin lower, it will connect at a higher rate, but will re-sync more often.
I'm about 420m from the cab which is equipped with ECI DSLAMs. At 6 dB SNR margin I get about 65Mb. At 3dB margin I can get 79Mb. I'm on the latest 3.8.4.3BT F/W. Hardware acceleration is turned off and currently the line is not interlaced in either direction (status shows 'Fast').
If I re-connect the BT supplied (ECI) modem, the line remains stable with no re-syncs. I have had the engineer out to test the connection, and his equipment indicated ther were no problems and he got similar 63Mb connection speeds at 7dB SNR.

I'm continuously collecting logs from the 2860, and graphing the SNR over time displays a nice curved sawtooth as the SNR reduces to zero and jumps up again after the re-sync.

So, why does the Draytek gradually lose SNR? It's as thought it heats up, or loses sensitivity or something, but if it were temperature related then it's unlikely that a quick re-sync would allow it to recover to the expected SNR again. The BT modem does not show this problem, but then again I cant get visibility as it's all locked down.

Are Draytek aware of this issue? Are there any specific settings to resolve this?

Thanks, Alistair

Hi Alistair, what you describe exactly matches my experience with 2860n+ connecting to Zen Internet via Broadcom DSLAM. Here's what I've tested:

3.8.4.2_BT = 3-4 disconnects per day (SNR starts at 6 dB each time then falls until line drops)
Zen supplied Technicolor TG589vn = very stable, only one disconnect in 7 days
3.8.2.3_BT = better than 3.8.4.2_BT but still 1-2 disconnects per day
At this point the exchange DSLAM resets my SNR to 15 dB due to all the disconnects!
3.8.4.3_BT (with default 576d17 modem code) = no disconnects (due to increased SNR) but router is constantly cycling SNR over 4-6 hours from 15 -> 6 -> 15
3.8.4.3_BT (with alternative 574307 modem) = no disconnects, SNR stable 12-14 dB over 48 hours

My understanding is that the router should decrease the SNR to achieve maximum line speed but, for some reason, 576d17 just continues until there's no signal left !!!
I have a ticket open with Tech Support who have recommended the following:
(1) If line drops, switch to alternative modem code in WAN/General |Setup/WAN1 - done
(2) Try adjusting routers SNR (see http://www.draytek.com/en/faq/faq-connectivity/connectivity.wan/how-to-adjust-adsl-snr-value-(for-vigor130/2760/2860-only)/ ) - does not work for me, is overruled by DSLAM setting
(3) Upgrade to 3.8.4.3_BT as this version address some issues related to WAN connection - done

Next step for me is to get the line reset back to 6dB then run some speed tests to see if the alternate modem code has any effect. Another possibility will be to try firmware vector1/2/3 ......