Network configuration

The network is already configured when the server is provisioned and works out of the box. You rarely edit the configs by hand — mostly to add an additional IPv4 or set up IPv6. A mistake in the network config can cut off SSH access: change one parameter at a time and immediately check access from a second window without closing your current session. As a last resort, reinstalling the system will bail you out (it wipes data).

Additional IPv4

There’s no button in the bot to order an extra IP — an additional IPv4 is issued through support @lumisup_robot. Once they send you the address, netmask, and gateway, set them in the OS.

Ubuntu (Netplan)
Debian (interfaces)
Windows

Modern Ubuntu uses Netplan. The config lives in /etc/netplan/ (a file like 01-netcfg.yaml or 50-cloud-init.yaml). Check the interface name with ip a (often eth0 or ens3) and add the second address to the addresses list:

/etc/netplan/01-netcfg.yaml

network:
  version: 2
  ethernets:
    eth0:
      addresses:
        - 192.0.2.10/24
        - 192.0.2.11/24
      routes:
        - to: default
          via: 192.0.2.1
      nameservers:
        addresses:
          - 1.1.1.1
          - 8.8.8.8

Here 192.0.2.10 is the primary IP and 192.0.2.11 is the added one. Substitute your own values.Check the syntax and apply:

netplan try
netplan apply

netplan try applies the config temporarily and automatically rolls it back after 120 seconds if you don’t confirm. Handy for not losing access over a typo.

On Debian 12, the eth0:0 alias method via /etc/network/interfaces may not work — it depends on what manages the network (ifupdown, systemd-networkd, or NetworkManager). The safer approach is to first test with ip addr add and then decide how to make it permanent.Temporarily (until reboot):

sudo ip addr add 192.0.2.11/24 dev eth0

Confirm the address came up (ip a) and check that the server is reachable from outside.

Making it permanent depends on the distro’s network stack: ifupdown, systemd-networkd, or NetworkManager — each has its own way. If you’re unsure about your configuration, ask support @lumisup_robot: an additional IPv4 in Lumi is issued through support anyway, and they’ll help with the setup too.

On Windows Server, an extra IP is added through the adapter properties:

Open the adapter settings

Win + R → ncpa.cpl → right-click the network adapter → Properties.

Open the IPv4 settings

Select Internet Protocol Version 4 (TCP/IPv4) → Properties → Advanced.

Add the IP

In the IP addresses section, click Add, enter the address and subnet mask you were given. Save the changes.

IPv6

If you’ve been given an IPv6 address and gateway, set them up the same way.

Ubuntu (Netplan)
Debian (interfaces)

/etc/netplan/01-netcfg.yaml

network:
  version: 2
  ethernets:
    eth0:
      addresses:
        - "2001:db8:abcd::2/64"
      routes:
        - to: "::/0"
          via: "2001:db8:abcd::1"

to: "::/0" is the default route for IPv6 (the equivalent of default for IPv4). Apply with netplan apply.

/etc/network/interfaces

iface eth0 inet6 static
    address 2001:db8:abcd::2
    netmask 64
    gateway 2001:db8:abcd::1

Apply: systemctl restart networking.

Check that IPv6 came up and connectivity works:

ip -6 a
ping6 -c 4 google.com

Check the network

Check addresses and interfaces

ip a

Look at the routing table

ip route

Check connectivity to the outside

ping -c 4 1.1.1.1

Diagnose packet loss (MTR)

If the connection keeps dropping, look at the route with MTR (it combines ping and traceroute):

apt install mtr-tiny
mtr 1.1.1.1

Firewall (ufw)

Open the ports you need, close off the rest.

Reverse DNS (PTR)

A reverse record for your IP.

VPS not working

Access, load, IP on blocklists.

​Additional IPv4

​IPv6

​Check the network

Firewall (ufw)

Reverse DNS (PTR)

VPS not working

Additional IPv4

IPv6

Check the network