8mbps difference between speedtest and sync

My setup with TTB is a Zyxel VMG-1312B10A connected to an Asus RT-AC68U router. My sync down is 69384kbps my speedtest is https://www.thinkbroadband.com/speedtest/16714220707... 61.9mbps as seen in the link. Why is my download roughly about 8mbps lower than sync. Have rebooted router and modem. Any ideas?

Download speed is always going to be lower than sync speed due to overheads such as packet envelopes. Much the same as the fact that a disk’s data capacity is always going to be less than its raw capacity.

The details are explained on the Kitz website
https://kitz.co.uk/adsl/IPprofile.htm

You're on a Huawei cabinets with G.INP (Retx)

Retx Low has an IP Profile right 96.7% of the sync speed, so throughput will be just under that.
Retx High has an IP Profile between 91-92% of the sync speed, with throughput just under that.

So the low throughput suggests Retx High to me. Check the stats to confirm.

Run the xdslcmd info --stats command

If Bearer 0, INPRein = 1 then you are on Retx High.
If Bearer 0, INPRein = 0 then you are on Retx Low.

If you are indeed on Retx High then you can temporarily cap your sync speed to about 60Mb/s and it should nudge the DLM to Retx Low.

adsl info --stats
adsl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 11304 Kbps, Downstream rate = 69343 Kbps
Bearer: 0, Upstream rate = 11297 Kbps, Downstream rate = 69384 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 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): 3.3 6.4
Attn(dB): 19.8 0.0
Pwr(dBm): 12.7 7.6

VDSL2 framing
Bearer 0
MSGc: -6 26
B: 243 237
M: 1 1
T: 0 50
R: 10 16
S: 0.0000 0.6697
L: 18146 3034
D: 8 1
I: 254 127
N: 254 254
Q: 8 0
V: 0 0
RxQueue: 75 0
TxQueue: 15 0
G.INP Framing: 18 0
G.INP lookback: 15 0
RRC bits: 0 24
Bearer 1
MSGc: 154 -6
B: 0 0
M: 2 0
T: 2 0
R: 16 0
S: 6.4000 0.0000
L: 40 0
D: 3 0
I: 32 0
N: 32 0
Q: 0 0
V: 0 0
RxQueue: 0 0
TxQueue: 0 0
G.INP Framing: 0 0
G.INP lookback: 0 0
RRC bits: 0 0

Counters
Bearer 0
OHF: 0 973421
OHFErr: 0 66
RS: 2326359696 2291226
RSCorr: 1586867 435
RSUnCorr: 0 0
Bearer 1
OHF: 26615159 0
OHFErr: 0 0
RS: 266150973 0
RSCorr: 74 0
RSUnCorr: 0 0

Retransmit Counters
rtx_tx: 462156 0
rtx_c: 124693 0
rtx_uc: 257 0

G.INP Counters
LEFTRS: 88 0
minEFTR: 69383 0
errFreeBits: 3570676038 0

Bearer 0
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 1207370660 0
Data Cells: 325662698 0
Drop Cells: 0
Bit Errors: 0 0

Bearer 1
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 0 0
Data Cells: 0 0
Drop Cells: 0
Bit Errors: 0 0

ES: 3 1065
SES: 0 0
UAS: 66 66
AS: 427579

Bearer 0
INP: 52.00 0.00
INPRein: 1.00 0.00
delay: 0 0
PER: 0.00 8.40
OR: 0.01 30.45
AgR: 69455.05 11327.28

Bearer 1
INP: 4.50 0.00
INPRein: 4.50 0.00
delay: 3 0
PER: 16.06 0.01
OR: 79.68 0.01
AgR: 79.68 0.01

Bitswap: 56840/56840 6453/6453

Total time = 70 days 1 hours 9 min 55 sec
FEC: 24023146 6483
CRC: 7 1182
ES: 3 1065
SES: 0 0
UAS: 66 66
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 15 minutes time = 9 min 55 sec
FEC: 1776 0
CRC: 0 0
ES: 0 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: 2546 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 = 1 hours 9 min 55 sec
FEC: 12562 11
CRC: 0 2
ES: 0 2
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 1 day time = 24 hours 0 sec
FEC: 390019 93
CRC: 0 12
ES: 0 12
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Since Link time = 4 days 22 hours 46 min 19 sec
FEC: 1586867 435
CRC: 0 66
ES: 0 62
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
NTR: mipsCntAtNtr=0 ncoCntAtNtr=0
>

Thanks John here's my stats. Can you tell from these?

Yep. Bearer 0 INPRein 1 means you're on Retx High and that consumes a lot of unnecessary overhead.

If it were my line I would apply a temp cap and try get Retx Low. It should only take a few days.

adsl configure --maxDataRate 50000 20000 100000

Applying the cap will resync the line once. The DLM should then resync the line in a few days changing it to Retx Low (if it works, which it usually does).

You're watching for this stat changing from 1.00 to 0.00

Bearer 0
INP: 52.00 0.00
INPRein: 1.00 0.00

Edited by j0hn83 (Tue 20-Dec-22 18:26:59)

Cheers John now sync'ing at 50mbps will keep an eye on stats.

https://www.thinkbroadband.com/speedtest/16718315701...

All sorted I think sync now 67.5mbps and speedtest as above 62mbps with INRein set at 0.00.