20.02.1 R-Pi4 IPv6, can get IP, ping works but IPv6 test fails

Hi all

I have finally upgraded my Raspberry Pi4 router from a custom snapshot build to 20.02.1, I have used Image Builder to include the packages I use and most important, the configuration.

My ISP provide a /64 (I know, I know) 6rd IPv6 connectivity that I made working with snapshot.

After moving to 20.02.1 I am getting a really weird issue, I faild the https://ipv6-test.com/ with the attached screenshot,

but I am able to ping with IPv6, I can resolve IPv6 host

C:\Users\menio>ping -6 www.google.com

Esecuzione di Ping www.google.com [2a00:1450:4002:404::2004] con 32 byte di dati:
Risposta da 2a00:1450:4002:404::2004: durata=10ms
Risposta da 2a00:1450:4002:404::2004: durata=8ms
Risposta da 2a00:1450:4002:404::2004: durata=8ms

Statistiche Ping per 2a00:1450:4002:404::2004:
    Pacchetti: Trasmessi = 3, Ricevuti = 3,
    Persi = 0 (0% persi),
Tempo approssimativo percorsi andata/ritorno in millisecondi:
    Minimo = 8ms, Massimo =  10ms, Medio =  8ms
C:\Users\menio>nslookup www.google.com
Server:  UnKnown
Address:  fdb7:fae9:33d3::1

Risposta da un server non autorevole:
Nome:    www.google.com
Addresses:  2a00:1450:4002:404::2004

and I can also access to http://http://[2a00:1450:4002:404::2004].
It is also happening that after some seconds I may loose the capability to ping ipv6 from clients, it gets restored after a reboot. Router ipv6 is always fine instead

It is worth to mention I am using ubound as resolver

Can you help me and point where to start troubleshooting?


Ok I found the issue

The Router is not advertising itself as default router, I can fix it adding:

route add ::/0 2001:xxx:xxxx:xxxx::1

but I am not sure why it is not happening automatically