ICMP6, destination unreachable, unreachable address aaaa:bbbb:cccc🅰xxxx:yyyy:zzzz:qqqq, length 112

Another newbie question about ipv6.

I am trying to setup ipv6 is my classic 2 vyos router network with a dmz .

I am for both on vyos stream 2025.11 .

Ipv4 works for more then a year and now I am trying to setup ipv6.

The internet facing router connect via ppp0e to my provider and gets the ipv4 and ipv6 address with no problem. I can ping ipv6 addresses from this router and get a response.

The internal router gets a correct ipv6 address too via RA.But when I try to ping from the internal router I get this error message.

ICMP6, destination unreachable, unreachable address aaaa:bbbb:cccc:a:xxxx:yyyy:zzzz:qqqq (ipv6 DMZ address internal router), length 112. Testing is done with firewall open (not wise I know)

I dont understand what I am doing wrong.

Here is my configuration of my internet router

set interfaces pppoe pppoe1 authentication password '1234'
set interfaces pppoe pppoe1 authentication username 'fake@bla'
set interfaces pppoe pppoe1 dhcpv6-options pd 0 interface eth0.10 address '1'
set interfaces pppoe pppoe1 dhcpv6-options pd 0 interface eth0.10 sla-id '10'
set interfaces pppoe pppoe1 dhcpv6-options pd 0 interface eth0.80 address '1'
set interfaces pppoe pppoe1 dhcpv6-options pd 0 interface eth0.80 sla-id '80'
set interfaces pppoe pppoe1 dhcpv6-options pd 0 length '56'
set interfaces pppoe pppoe1 dhcpv6-options rapid-commit
set interfaces pppoe pppoe1 ip adjust-mss 'clamp-mss-to-pmtu'
set interfaces pppoe pppoe1 ipv6 address autoconf
set interfaces pppoe pppoe1 mtu '1492'
set interfaces pppoe pppoe1 source-interface 'eth1.6'
set service router-advert interface eth0.10 link-mtu '1492' 
set service router-advert interface eth0.10 name-server 'ipv6 dns server' 
set service router-advert interface eth0.10 prefix ::/64 valid-lifetime '172800' 

ip adresss on eth0.10 aaaa:bbbb:cccc:a::1/64

Configuration internal router:

set interfaces ethernet eth0 vif 10 address ‘dhcpv6’
set interfaces ethernet eth0 vif 10 description ‘eth0.10 - DMZ Tagged’
set interfaces ethernet eth0 vif 10 ipv6 address autoconf

ipv6 address obtained through RA aaaa:bbbb:cccc:a:xxxx:yyyy:zzzz:qqqq/64

Strangely remove this 2 commands fixed my problem

set interfaces pppoe pppoe1 dhcpv6-options pd 0 interface eth0.10 address '1'
set interfaces pppoe pppoe1 dhcpv6-options pd 0 interface eth0.80 sla-id '80'