Trouble with ipv6 Stateless configuration for new vms

[munntj]

Ever since I upgraded to pve6 from pve6 my ipv6 address SLAAC seems broken. "Old" vms with exisiting ips work fine, but new ones will initially get an ip address for ipv6, and then next reboot won't. I can't figure out why its happening, different network adapters, different oses etc. simply don't reliably work with ipv6 slaac anymore. I did at one time try the iproute2 and thats when everything blew up. I went back to iproute, but now my network for new machines is totally unusable. Any ideas? My "external" interface is vmbr0.

 

[munntj]

# network interface settings; autogenerated
# Please do NOT modify this file directly, unless you know what
# you're doing.
#
# If you want to manage parts of the network configuration manually,
# please utilize the 'source' or 'source-directory' directives to do
# so.
# PVE will preserve these directives, but will NOT read its network
# configuration from sourced files, so do not attempt to move any of
# the PVE managed interfaces into external files!

auto lo
iface lo inet loopback

iface eno1 inet manual

iface eno2 inet manual

auto vmbr0
iface vmbr0 inet static
    address  63.141.232.50
    netmask  29
    gateway  63.141.232.49
    bridge-ports eno1
    bridge-stp off
    bridge-fd 0

iface vmbr0 inet6 auto

auto vmbr2
iface vmbr2 inet static
    address  192.168.1.0
    netmask  24
    bridge-ports none
    bridge-stp off
    bridge-fd 0

auto vmbr3
iface vmbr3 inet static
    address  172.16.1.0
    netmask  24
    bridge-ports none
    bridge-stp off
    bridge-fd 0
    bridge-vlan-aware yes
    bridge-vids 2-4094

auto vmbr1
iface vmbr1 inet static
    address  10.5.0.0
    netmask  16
    bridge-ports none
    bridge-stp off
    bridge-fd 0