Routed Network Config

[timdemand]

Hi,

I've tried to setup a routed network for the past hours with the official guide and then some others I could find online but I haven't gotten it to work right...
My current "/etc/network/interfaces" looks like this:

auto lo
iface lo inet loopback

#First IPv4
auto ens18
iface ens18 inet static
        address 45.xxx.xxx.51/32
        pointtopoint 45.xxx.xxx.1
        gateway 45.xxx.xxx.1

#IPv6
iface ens18 inet6 static
        address 2a00:xxxx::0/64
        gateway fe80::1

#Second IPv4
auto vmbr0
iface vmbr0 inet static
        address 45.xxx.xxx.51/32
        bridge-ports none
        bridge-stp off
        bridge-fd 0
        post-up ip route add 37.xxx.xxx.22/32 dev vmbr0

#IPv6
iface vmbr0 inet6 static
        address 2a00:xxxx::1/64
        post-up ip -6 route add 2a00:xxxx::/64 dev vmbr0

#IPv4 NAT
auto vmbr1
iface vmbr1 inet static
        address 10.0.0.1/24
        bridge-ports none
        bridge-stp off
        bridge-fd 0

#IPv6
iface vmbr1 inet6 static
        address 2a00:xxxx::2/64
        post-up ip -6 route add 2a00:xxxx::/64 dev vmbr1

post-up sysctl -p
post-up echo 1 > /proc/sys/net/ipv4/conf/ens18/proxy_arp

post-up iptables -t nat -A POSTROUTING -s '10.0.0.0/24' -o ens18 -j MASQUERADE
post-down iptables -t nat -D POSTROUTING -s '10.0.0.0/24' -o ens18 -j MASQUERADE

IP-Forwarding is configured with sysctl.conf

How it is supposed to work:
ens18 for proxmox should have my first public ipv4 and a public ipv6
vmbr0 for one specific vm should have the other public ipv4 and a public ipv6
vmbr1 is for all other vms that dont need a separate ipv4, they share with proxmox using NAT but can have a seperate ipv6

I can access proxmox with both IPv4 and v6 (ens18) and VM's with NAT (vmbr1) but only IPv4, the dedicated IPv6 addresses don't work.
The second public IPv4 is also not working.

Is there something I am missing?

Thanks
Tim