7490 better at VDSL2 than 7390

[frater]

I am running over 50 Fritzboxes that are heavily monitored using Zabbix.
Since a year we have more and more places where VDSL2 is possible where we have ADSL-2 running.

Upgrading these places to VDSL2 caused all lines to become unstable until we replaced these with a 7490.

Do you have the same experience?
Is it a hardware thing or a software thing (the software that's actually driving the DSL)?

 

[MuP]

The 7390 uses a Ikanos chipset.
The 7490 uses a Lantiq chipset, that's better but only on some lines.

 

[frater]

The 7390 uses a Ikanos chipset.
The 7490 uses a Lantiq chipset, that's better but only on some lines.

Thanks a lot for this info. I didn't know this.
It also means it can't be solved with software then.

Our experience after 5 of these upgrades is that all 7390's become unstable moving from ADSL-2 to VDSL-2
Replacing the 7390 with a 7490 turned these lines to super stable besides one.

The line that still isn't stable with a 7490 did improve, but is still not rock solid (like the other 4)

One 7390 was still unstable after we downgraded the line to 50 Mbit/s and moved all the sliders to the left.
It then trained on 25 Mbit/s and it still had extreme packetloss from time to time (packetloss is measured 24/7 from a remote server on all our lines with Zabbix).

Now this line is training @ 110 Mbit/s with a 7490 and never drops a beat.

The 7490 that is still unstable is in Rotterdam whilst all the other lines are in Amsterdam. They might have different equipment in their central.
This or there's something wrong with that particular line.