Oddly I would have thought with such a loss of throughput G.INP would be changed to Interleave as Vdsl 2 can use much greater interleaving depths, the maximum interleaving depth is 3072 (for profile 17a) so 4 with that drop seems odd hence my mention of it. My Interleaving is 1087 when it was on fast path before the modem change, on an ECI cab. If the poster is on a Huawei cab I would have thought that interleaving would have been applied until the line was stable then G.INP reapplied at some point. Since not everyone is having re-syncs saying what cab they are on would help in this thread. What do you think?
My thoughts... I'll try cover all your points.
The DLM doesn't ever change from G.INP to interleaving.
G.INP is the default on Huawei cabinets.
G.INP is now retained after a DLM reset or ISP migration (recent change).
New activations on Huawei cabinets have Interleaving applied for 2 days then G.INP is applied instead. That may also have changed and G.INP might even be applied immediately.
The Interleaving depth is usually 4 or 8 with G.INP applied.
It's only in the hundreds/thousands if INP/interleaving is applied instead.
The loss of throughput is due to the DLM increasing the target SNRM (noise margin).
The default target is 6dB down and up.
It's always 6dB on the upstream.
It's always 6dB on the downstream on ECI cabinets (due to no completed G.INP rollout).
If a line with G.INP in a Huawei cabinet is stable enough and has low enough errors the DLM lowers the target downstream SNRM to 5, 4 or 3dB, in 1dB steps.
There's 3 users in this thread with the Vigor 166 on VDSL2 who have had the DLM increase the target SNRM since connecting the Draytek.
This is due to an increase in errors. With the Draytek connected the DLM would never have lowered the target from 6dB in the 1st place.
At least 1 of the lines have gone from 3db to 4db to 5db all the way back to 6dB.
That's a considerable drop in stability compared to the users previous modem.
That's why having the error counters fixed is so important.
It's impossible to tell how stable the chipset is or how good/poor it is performing without being able to see the stats.
It's impossible to tell if each new firmware revision improves performance or not.
They say it should fix the stats showing '0' but not in my case...
Well that's a shame.
I'm very interested in seeing the full stats in the hope of seeing what's going on that's making the DLM so harsh.
It's a shame as the Vigor 130 is rock solid and lines regularly drop to 3dB using it.
I wonder if the Vigor 165 suffers the same 0 errors bug.
So far my Google search has been futile.