Server with multiple external ips

[military1]

Hello!
I ask for help. I’ve been reading for several days, but haven’t found a solution.

I ask for help. I’ve been reading for several days, but haven’t found a solution.
Simple task. There is a server with 5 ip addresses. Open server is installed with only 1 ip address (main). How to make sure that the remaining 4 addresses also work in the open server?
In the client file I will write the host name, which will be redirected to the server by the dns. It tried, it works.
But I just need OpenVPN to work with all 5 ips on this server.
/etc/network/interfaces:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The normal eth0
allow-hotplug eth0
iface eth0 inet dhcp

# Additional interfaces, just in case we're using
# multiple networks
allow-hotplug eth1
iface eth1 inet dhcp

allow-hotplug eth2
iface eth2 inet dhcp

# Set this one last, so that cloud-init or user can
# override defaults.
source /etc/network/interfaces.d/*

[randshell]

1. OpenVPN config file:
   local x.x.x.x
   #88

2. Firewall:
   iptables -t nat -A PREROUTING -d {secondary-ip} -p udp --dport 1882 -j DNAT --to-destination {main-ip}:{main-ip-port}

udp becomes {protocol} and 1882 {secondary-ip-port}