VDSL connectivity problems

Installing and Using OpenWrt Network and Wireless Configuration
1

Hi all!

I have connectivity problems since I switched from ADSL to VDSL some days ago. The router reconnects every 12-48 hours for no obvious reason. With ADSL the link was connected for weeks.

My router is a TD-W8970 with OpenWrt 18.06.1 r7258-5eb055306f, the provider is telekom.de.

system log:

Wed Oct 24 19:31:28 2018 daemon.err uhttpd[1010]: luci: accepted login on /admin/status/overview for root from 10.8.20.10
Wed Oct 24 19:32:09 2018 kern.warn kernel: [120934.076430] leave showtime
Wed Oct 24 19:32:09 2018 daemon.notice netifd: Network device 'dsl0' link is down
Wed Oct 24 19:32:09 2018 daemon.notice netifd: VLAN 'dsl0.7' link is down
Wed Oct 24 19:32:09 2018 daemon.notice netifd: Interface 'wan' has link connectivity loss
Wed Oct 24 19:32:10 2018 daemon.notice netifd: Interface 'wan6' is now down
Wed Oct 24 19:32:10 2018 daemon.notice netifd: Interface 'wan6' is disabled
Wed Oct 24 19:32:10 2018 daemon.notice netifd: Network alias '' link is down
Wed Oct 24 19:32:10 2018 daemon.notice netifd: Interface 'wan6' has link connectivity loss
Wed Oct 24 19:32:10 2018 daemon.info pppd[2418]: Terminating on signal 15
Wed Oct 24 19:32:10 2018 daemon.info pppd[2418]: Connect time 2012.7 minutes.
Wed Oct 24 19:32:10 2018 daemon.info pppd[2418]: Sent 400046161 bytes, received 1720930632 bytes.

dsl_control status (5 mins after link went down and was up again):

ATU-C Vendor ID:                          Broadcom 192.85
ATU-C System Vendor ID:                   Broadcom
Chipset:                                  Lantiq-VRX200
Firmware Version:                         5.9.0.12.1.7
API Version:                              4.17.18.6
XTSE Capabilities:                        0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x2
Annex:                                    B
Line Mode:                                G.993.5 (VDSL2 with down- and upstream vectoring)
Profile:                                  17a
Line State:                               UP [0x801: showtime_tc_sync]
Forward Error Correction Seconds (FECS):  Near: 0 / Far: 0
Errored seconds (ES):                     Near: 14 / Far: 2
Severely Errored Seconds (SES):           Near: 1 / Far: 0
Loss of Signal Seconds (LOSS):            Near: 0 / Far: 0
Unavailable Seconds (UAS):                Near: 243 / Far: 243
Header Error Code Errors (HEC):           Near: 0 / Far: 0
Non Pre-emtive CRC errors (CRC_P):        Near: 1 / Far: 0
Pre-emtive CRC errors (CRCP_P):           Near: 0 / Far: 0
Power Management Mode:                    L0 - Synchronized
Latency [Interleave Delay]:               0.13 ms [Fast]   0.0 ms [Fast]
Data Rate:                                Down: 50.802 Mb/s / Up: 11.524 Mb/s
Line Attenuation (LATN):                  Down: 23.5 dB / Up: 32.0 dB
Signal Attenuation (SATN):                Down: 21.5 dB / Up: 31.5 dB
Noise Margin (SNR):                       Down: 6.1 dB / Up: 9.2 dB
Aggregate Transmit Power (ACTATP):        Down: 9.5 dB / Up: 14.3 dB
Max. Attainable Data Rate (ATTNDR):       Down: 55.640 Mb/s / Up: 12.306 Mb/s
Line Uptime Seconds:                      293
Line Uptime:                              4m 53s

Maybe it's just coincidence, but this was the second time the link went down shortly after (30 secs) I logged in to luci.

I found some similar topics with random reconnects on the forum, but no solution so far.

Anyone has an idea what can cause the connectivity losses?

Thanks!

2

We use vdsl here, no issues.

You should try to get this to work first with stock fw to rule out that your modem or hardware connections from providers end aren't at fault.

There are modem specific setting you may need to play with as well.

3

Hm yes.

This is not so easy, the TP-Link firmware does not support VDSL. And since I'm using OpenWRT for years I never owned a router from my provider :sunglasses:.

4

my dtag vdsl-link also got a lot more flaky recently.
it correlated well with the introduction of the 250mbps vdsl offering, so i speculate that the dsl-spectrum probably got more cowded.
dont know if that applies to you, but it should be warranted to open a support-ticket with telekom and have them check.

5

Hi!

My provider said the line is OK.

it correlated well with the introduction of the 250mbps vdsl offering, so i speculate that the dsl-spectrum probably got more cowded.

I was not able to get VDSL until 2 weeks ago, only ADSL was possible. I think the reason for getting VDSL now was because Telekom enabled vectoring.

6

Once vectoring is enabled in your cabinet, only vectoring capable modems (hardware and firmware) will be able to connect; there should be a 16 MBit/s fallback profile though.

7

I can connect and vectoring is working, please see my first post. I get randomly disconnected and don't know why.

8

did your problem start at this time?

9

Yes, never had any problems with the same router and the ADSL link.

10

There is likely to be some sporadic source of electrical noise or RF interference affecting your line. Vectoring and G.INP make VDSL more resilient but when the noise or interference exceeds what they can cope with you'll get dropouts or (if SRA is enabled and functioning) sync rate reductions.

The VDSL2 rollout in Australia is littered with complaints about this sort of signal dropout, at least in part because of the age and condition of much of the old copper POTS network :frowning: and I experience its myself (with a TD-W8980 running OpenWRT, a Fritz!Box 7490 and several brands of modem/router with Broadcom xDSL chipsets - they all suffer). If you can borrow a modem with a Broadcom chipset it would be a good idea to test whether it also experiences the dropouts.

11

Update:

It looks like that DLM (dynamic line management) is enabled on my link. The UL data rate got reduced to 35 Mb/s. But there are still one or two reconnects per day, although there are very few errors.

Errors before reconnect with line uptime over 1 day:

Line Mode: G.993.5 (VDSL2 with down- and upstream vectoring)
Profile: 17a
Line State: UP [0x801: showtime_tc_sync]
Forward Error Correction Seconds (FECS): Near: 0 / Far: 1
Errored seconds (ES): Near: 1 / Far: 78
Severely Errored Seconds (SES): Near: 0 / Far: 60
Loss of Signal Seconds (LOSS): Near: 0 / Far: 0
Unavailable Seconds (UAS): Near: 191 / Far: 191
Header Error Code Errors (HEC): Near: 0 / Far: 0
Non Pre-emtive CRC errors (CRC_P): Near: 0 / Far: 0
Pre-emtive CRC errors (CRCP_P): Near: 0 / Far: 0

Errors afte reconnect:

Line State: UP [0x801: showtime_tc_sync]
Forward Error Correction Seconds (FECS): Near: 0 / Far: 0 
Errored seconds (ES): Near: 1 / Far: 78
Severely Errored Seconds (SES): Near: 0 / Far: 60
Loss of Signal Seconds (LOSS): Near: 0 / Far: 0 
Unavailable Seconds (UAS): Near: 301 / Far: 301
Header Error Code Errors (HEC): Near: 0 / Far: 0 
Non Pre-emtive CRC errors (CRC_P): Near: 0 / Far: 0
Pre-emtive CRC errors (CRCP_P): Near: 0 / Far: 0

This shows there where no errors (at least none which are shown in the stats) to trigger the reconnect.

On the weekend I will get a router from my provider (Speedport SMART 2) with a Broadcom chip.

12

Update:

I have the Speedport SMART 2 connected to my OpenWRT router in modem only mode (bridge mode) and the connection is up for 5 days now.

So it really seems that the Lantiq chip has issuses with vectoring on long lines.

13

It can also be related to the firmware, although I am not sure myself. I am using a Tp-Link TD-W8980 myself and I compiled a custom DSL firmware from FritzBox 7490. The guide is somewhere here in the forum. The custom firmware gives me better stats on my line, when the Openwrt's default firmware provides something similar to my ISP's Broadcom router. But it can be a lot of reasons, hardware, software, line, ISP's issue etc.

14

I had tried 2 or 3 different Lantiq DSL firmwares. The one in the image did not support vectoring.