IPv6 with Fritz!Box 7390 on FTTC

[#1]

Environment: I'm using the Openreach ECI NTE connecting to a Fritz!Box 7390.  I was previously using the Fritz VDSL2 modem directly, but after months at a stable 40Mbps after switching to the Fritz I discovered that DLM slowly reduced the line speed down to 22Mbps.  Since switching back to the ECI my speed has begun to increase again!
Configuring IPv6 on the Fritz is trivial, just head to the IPv6 tab and enable it!

After a PPP reconnect, the status shows the allocation:

The Fritz defaults to blocking inbound IPv6, but it is easy to selectively enable access to hosts for full-access or limited to specific protocols/ports:

The Fritz keeps track of IPv6 address allocations per-host, including privacy addressing, so there are no problems caused by addresses changing over time:

I added an AAAA record for my iMac, using it's permanent address (not one of the random privacy addresses; that will not accept inbound connections), and I can now access it from anywhere I have IPv6 connectivity.  This does mean I am relying on the iMac's firewall (pf) to control access.
Overall I am very happy.  Latency is comparable to IPv4, and based on the ThinkBroadband ping monitor it has been 100% stable since activation:

Thanks to the Plusnet team for the work to make this happen.  I am looking-forward to this going fully-live and having this enabled on my personal Plusnet account.
Doug

[#2]

Hi DougMa,
I also found the F!B configuration very straightforward but I have one anomaly that you could perhaps check:
If you set up both IPv4 and IPv6 ping monitors, does the IPv6 one show predominantly lost packets (mostly red) when the IPv4 one is also running?
Is your ping monitor set up for the Fritz!Box IPv6 address (the one shown in the 'Online Monitor' screen)?

[#3]

Hi w23,
I have observed the same; as a result I've always monitored either IPv6 or IPv4, never both at the same time.  I've also found that IPv4 monitoring always shows a % packet loss:

I used IPv4 monitoring when using an HE tunnel for IPv6 because my priority was monitoring the WAN link rather than the WAN link plus tunnel.  Now I'm running native IPv6, I prefer to use that for monitoring since it doesn't exhibit the same % packet loss as the IPv4 monitoring.
My guess is that WAN ping responses over IPv4 are given such a low priority that they are dropped rather than added to the output queue behind any "production" traffic.
Edit: I just ran a continuous IPv4 ping to test, and you can see the effect on the live monitor in my previous post: significant packet loss for the IPv6 monitor.  I am convinced this is a Fritz implementation side effect rather than any issue with Plusnet's IPv6 support.
Doug

[#4]

Thanks for confirming DougMa, I also concluded it was a Fritz!Box issue as it happened on the previous trial (and only seemed to be me at that time).