Same network config works in Stretch, stalls in Wheezy

[moxfan]

Hi Guys,

Why is it that the network configuration below, on the same server, works great with Proxmox 5.1 & Debian 9, but does not boot with Proxmox 3.4 & Debian 7 (just replaced eno1 and eno2 with eth0 and eth1 in Debian 7)?

root@srv2:~# cat /etc/network/interfaces
auto lo
iface lo inet loopback
iface eno1 inet manual
auto vmbr0
iface vmbr0 inet static
    address XXX.XXX.XXX.24   <-- Host IP
    netmask 255.255.255.0
    gateway XXX.XXX.XXX.1
    bridge_ports eno1
    bridge_stp off
    bridge_fd 0
auto vmbr0:0
    iface vmbr0:0 inet static
    address XXX.XXX.XXX.74   <-- Failover IP
    netmask 255.255.255.255
auto eno2   <-- Vlan on second port
     iface eno2 inet dhcp
     mtu 9000