I recently installed PROXMOX VE 7.4 by performing the network settings in the installation utility itself, since then I have had difficulties getting my proxmox to ping on the local network or any other type of network connection.:
# cat /etc/network/interfaces
#brctl show
# cat /etc/network/interfaces
auto lo
iface lo inet loopback
iface enp7s0 inet manual
auto vmbr0
iface vmbr0 inet static
address 192.168.0.250/24
gateway 192.168.0.1
bridge-ports enp7s0
bridge-stp off
bridge-fd 0
iface enp4s0f0 inet manual
iface enp4s0f1 inet manual
#brctl show
bridge name bridge id STP enabled interfaces
vmbr0 8000.00e00a738627 no enp7s0