Changed VDSL modem to a known good one (a Zyxel and also a Draytek which are both mine, end up getting a similar line rate) but the issues remain. We've always had an issue with water ingress into the phone line so that is probably the most likely culprit but really, we need BT to replace the line from the mast as every time they 'fix' it, problems promptly return. I took the (5-10 year old) master socket and most of the pins were corroded with water damage. Replaced it with a brand new (5c) and still get about the same line rate. There are NO wired extensions connected as I removed them all some years ago and it is just the house phone and the modem that are connected to the master socket.
When I last lived here, it would sync at ~55mbit and now can't get it beyond 33. The symptoms of the internet issues are total connection drops (following 500 or so CRC errors as shown below). That's the simple one. The other issue that I cant narrow down is just poor performance. Speedtests will drop to 10mbit for a short period (5-10 mins) and occasionally, sites will just stop loading but it recovers itself sometimes without retraining the connection. Stats are below for my Zyxel VMG1312-B10A.
VDSL Training Status: Showtime
Mode: VDSL2 Annex B
VDSL Profile: Profile 17a
G.Vector: Disable
Traffic Type: PTM Mode
Link Uptime: 0 day: 0 hour: 2 minutes
====================================================================================
VDSL Port Details Upstream Downstream
Line Rate: 8.418 Mbps 29.998 Mbps
Actual Net Data Rate: 8.419 Mbps 29.999 Mbps
Trellis Coding: ON ON
SNR Margin: 6.3 dB 10.4 dB
Actual Delay: 0 ms 0 ms
Transmit Power: 4.4 dBm 12.5 dBm
Receive Power: -9.2 dBm -15.0 dBm
Actual INP: 44.0 symbols 54.0 symbols
Total Attenuation: 0.0 dB 23.0 dB
Attainable Net Data Rate: 8.419 Mbps 40.911 Mbps
====================================================================================
VDSL Band Status U0 U1 U2 U3 U4 D1 D2 D3
Line Attenuation(dB): 9.2 40.3 59.2 N/A N/A 17.7 47.7 73.9
Signal Attenuation(dB): 9.2 39.8 58.6 N/A N/A 25.7 47.3 76.8
SNR Margin(dB): 6.7 6.3 6.3 N/A N/A 10.4 10.4 10.4
TX Power(dBm): -0.1 -2.5 0.3 N/A N/A 10.6 7.7 -4.6
====================================================================================
VDSL Counters
Downstream Upstream
Since Link time = 2 min 19 sec
FEC: 13 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 15 minutes time = 14 min 18 sec
FEC: 2275 0
CRC: 575 0 ********** Shortly before the connection drop/retrain
ES: 11 0
SES: 11 0
UAS: 38 27
LOS: 1 0
LOF: 7 0
LOM: 0 0
Previous 15 minutes time = 15 min 0 sec
FEC: 52 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 1 day time = 22 hours 59 min 18 sec
FEC: 11241 7
CRC: 575 5
ES: 11 5
SES: 11 0
UAS: 66 55
LOS: 1 0
LOF: 7 0
LOM: 0 0
Previous 1 day time = 0 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Total time = 22 hours 59 min 18 sec
FEC: 11241 7
CRC: 575 5
ES: 11 5
SES: 11 0
UAS: 66 55
LOS: 1 0
LOF: 7 0
Wondering how to persue it, hopefully some here will come up with some good suggestions. Again, I imagine the only real solution would be to replace the line, but I imagine it will be very hard to convince BT to do that. The point where the phone line enters the house has been changed 3 times over the last 25 years due to water ingress and subsidence.
Cheers in advance!