Turns out that it is too early to write off VDSL2 as a less than robust technology, one that's hyper sensitive to cross-talk and interference.
As readers of my blog might recall, my VDSL2 connection dropped more than twenty megabit/s in speed despite the line itself being in good condition.
Chorus ran a bunch of tests on the line and said the large speed drop was due to other DSL deployments in the same feeder cable that increased the noise or cross-talk, interfering with my connection.
This turns out not to be the case. My ISP, Snap Internet, persuaded Chorus to apply the correct settings for my connection and I now have 67 megabits per second down and 10Mbps up again (I could have ~30Mbps if Chorus removed Telecom's old and pointless rate-limit).
The connection's back to the 17a profile with more spectrum than 8b. Interestingly enough, the modem now registers substantially fewer errors despite an increased amount of spectrum used.
As for the data connection, it's totally stable. Obligatory Speedtest result:
Chorus really needs to fix these sudden speed drops, as I'm not the only one seeing them. They are most likely caused by the Alcatel-Lucent Dynamic Line Management (DLM) feature that Chorus uses and which either does not work properly, or isn't set up right - I can't tell from my end of the connection.
Full marks to Snap for pursuing this and having the technical expertise to set it right.
Update Daniel Cull asked which configuration setting needs to be err, set, and it's Spectrum Profile Name: EUBAV-VDSL2-4
This is what the AVM Fritz!Box 7390 reports about the DSL connection on Profile 17a:
Update II Back to profile 8b. Alcatel-Lucent and Chorus are working on it, so fingers crossed, not for too long.
While they're at it, Chorus should remove the old Telecom-imposed 70Mbps down/10Mbps up rate limit, as per how ADSL2+ is configured - as fast as your line can go. Having 10Mbps up is great, 30Mbps or faster would be even better.
Other related posts:
The problem with VDSL2
The mysterious Dynamic Line Management on VDSL2
Patchy UFB coverage for Auckland?
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