The "Since Link Time" set of statistics looks rather worrying. 3,772 errored seconds means that CRCs happened in pretty much every single second of the 1 hour 6 minutes (3,960 seconds) of link uptime. And, with 201,000 CRCs in that time, that comes out to be very close to 50 CRCs per second ... very close to the 50 Hz AC rate of mains.
If that isn't electrically-induced noise, it is one heck of a coincidence.
You sir, are an absolute legend. This is what appears to be happening. The modem was sitting on top of a Netgear PoE switch and when I moved it away to a place with no other equipment nearby, CRC errors dropped massively.
Thank you for your help. Really appreciate it
Have been dealing with BT for a week on this and even had an engineer come out.
Once DLM kicked in, it kept dropping the line sync rate every day until BT engineer did a reset. BT engineer came out and did line tests which came out clean but when he ran VDSL tests on his device, he only got 39 Mbps down. So he went ahead and did a DLM reset. It was done yesterday so hopefully, DLM should kick in tomorrow and should see better results. Also, once FEC is enabled, it should help with CRC errors as well.
BT have an SFI engineer scheduled for Friday as even they were puzzled with actual speeds being so low when underlying line syncs at 70+ with the exchange. Maybe his visit isn't needed anymore. I will wait until Thursday to see how it goes before canceling the appointment.
BT HH6 doesn't seem to be affected by noise. Maybe it has better isolation compared to HG612. BT don't seem to be offering Modem mode like Virgin media does.
Latest stats
# xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 32261 Kbps, Downstream rate = 80648 Kbps
Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 79987 Kbps
Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode(0x0)
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 6.5 15.3
Attn(dB): 12.8 0.0
Pwr(dBm): 12.7 1.1
VDSL2 framing
Bearer 0
MSGc: 18 26
B: 239 237
M: 1 1
T: 23 42
R: 0 16
S: 0.0955 0.3781
L: 20104 5374
D: 1 1
I: 240 127
N: 240 254
Counters
Bearer 0
OHF: 2364758 985017
OHFErr: 1298 1
RS: 0 2697763
RSCorr: 0 15
RSUnCorr: 0 0
Bearer 0
HEC: 129 0
OCD: 3 0
LCD: 3 0
Total Cells: 601284678 0
Data Cells: 15771772 0
Drop Cells: 0
Bit Errors: 0 0
ES: 698 1
SES: 0 0
UAS: 23 23
AS: 3910
Bearer 0
INP: 0.00 0.00
INPRein: 0.00 0.00
delay: 0 0
PER: 1.65 3.98
OR: 116.09 64.22
AgR: 80103.09 20063.54
Bitswap: 1359/1359 0/0
Total time = 1 hours 5 min 33 sec
FEC: 0 15
CRC: 1298 1
ES: 698 1
SES: 0 0
UAS: 23 23
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 15 minutes time = 5 min 33 sec
FEC: 0 0
CRC: 85 0
ES: 64 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 15 minutes time = 15 min 0 sec
FEC: 0 3
CRC: 319 0
ES: 157 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 1 day time = 1 hours 5 min 33 sec
FEC: 0 15
CRC: 1298 1
ES: 698 1
SES: 0 0
UAS: 23 23
LOS: 0 0
LOF: 0 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
Since Link time = 1 hours 5 min 9 sec
FEC: 0 15
CRC: 1298 1
ES: 698 1
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
It is always useful to have a spare HG612 available, just in case of "one of those moments".
Take a look at the very first post of this thread. I will suggest that you research the various ZyXEL devices, at the bottom of that list. A number of members use such devices; some configured just as a pure-bridge modem, others configured at a full all-in-one box.
I am keeping the HG612 modem. Was wondering if newer modem provided better performance compared to HG612. Also they have firmware updates which HG612 doesn't.
Is there a reason why Draytek 130 VDSL modem isn't on the list? For a modem use case, it only costs £81 on Amazon compared to paying £100+ for VDSL router that I am only going to be using in bridge mode