Upstream oddity

Looking at a line with a minor problem in that the upstream appears slow. Tried with two different PCs - both wired Ethernet and the results are much the same.

TBB and BT Wholesale both give 15 to 17 Mbps
Speedtest.net 17 Mbps ( and I know it is often a little optimistic)

Sync is 19999 and Max attainable is around 25.5 to 26 Mbps with >10 dB SNR so it should give close to 19 Mbps and I cannot see any reason why it is slow. Minimal errors occurring - if any, short leads from modem to socket, no big unexpected dips in Bits/Tone graph and other graphs look fine too. No other devices uploading ... and is much the same at all times.

Downstream is syncing at a full 80 Mbps and gives 75.5 Mbps - so no issues there. Most recent BT test gave an actual 78.63 Mbps with 77.35 Mbps Max Achievable.

Just trying to work out what I may have missed ... as everything points towards full speed being achievable.

Any chance it could be because Upstream G.INP is activated, and is in "High Retransmission" mode?

Impossible to say without line stats. Could be anything.

Maybe your modem is backing off a bit for QOS (even if it's not explicit "user" QOS it may/should still prio some non ip traffic like ppp pings)

IIRC from unlocking an OR Huawei, it had QOS on somewhat below 20mbit affecting speed tests, in fact even turning off it was slightly weird vs the ECI which I still use, but with it off you wouldn't notice on a speed test.

The key stats were in the original post ...

The current snapshot - the achievable speeds vary by +/-200kbps and SNR by +/- 0.2 dB and no massive swings.

Max: Upstream rate = 25482 Kbps, Downstream rate 82688 Kbps
Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 80000 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): 6.7 9.9
Attn(dB): 16.7 0.0
Pwr(dBm): 13.5 7.1

No errors?

I reckon it may be because "High Retransmission" is enabled on the Upstream...

Did try that and found that with TBB there is a very slight improvement, BT much the same and speedtest.net pushes up to 18 (but never confident). I would hope to see >18.5 on both TBB and BT.

The errors counts are stable and have not moved on upstream.

Retransmit counters at zero, G.INP counters at zero

Weird, I would say it's the internal network side then, and not to do with the line itself...