DNS is blocked on the firewall for green, that’s really strange.
Maybe you just mixed up red/green interface?
In Proxmox you just mapped 1 interface to a vmbr but 2 interfaces are needed for a firewall/gateway.
It seems you set IPs for NethServer at Proxmox level, that’s not needed.
Here is an example of a 2 interface Proxmox config:
auto lo
iface lo inet loopback
auto enp2s0f0
iface enp2s0f0 inet manual
auto enp2s0f1
iface enp2s0f1 inet manual
auto vmbr0
iface vmbr0 inet static
address 192.168.1.20/24
gateway 192.168.1.11
bridge-ports enp2s0f0
bridge-stp off
bridge-fd 0
auto vmbr1
iface vmbr1 inet manual
bridge-ports enp2s0f1
bridge-stp off
bridge-fd 0
As regards shorewall issues, you may try to disable it to check if it’s just a shorewall issue.
shorewall clear
To reenable:
signal-event firewall-adjust