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Replacing a server's main IP address with a floating IP

Published on: September 29, 2026

A Cloud Server gets its main public IPv4 address when it is created. If you have also attached a floating IP to the same server, you might want the floating IP to become the server's main IP address and get rid of the original one.

To do this, you first delete the server's public IPv4 interface. This deletes the original IP address and detaches the floating IP, which stays in your account. You then create a new public IPv4 interface and select the floating IP as its address. This guide shows how to do that without losing access to your server.

If you want to do the opposite and turn a server's own IP address into a floating IP, see Converting a server IP address to a floating IP address.

Before you begin

Read these points before you make any changes:

The server is offline during the change. You need to shut the server down to delete and create network interfaces.
The original IP address is deleted permanently. You cannot get it back after you delete the interface.
The address can no longer be moved to another server. Once it is the interface's main IP address, it stops being a floating IP, so you cannot transfer it to another server or detach it.
Use the same interface index. The new interface must use the same index as the interface you delete. With a different index, the operating system can fail to configure the new interface, which leaves the server without an IPv4 address.
Keep a way into the server. You lose SSH access through the original IP address as soon as you shut the server down, and you reconnect using the floating IP afterwards. If something goes wrong, the web console in the Control Panel is your fallback. The console asks for a password, so if you log in with SSH keys only, set a password for the account you will log in with at the console before you start. On UpCloud templates this is root unless you have created your own user.

This guide covers the following operating systems, installed from the UpCloud templates:

Ubuntu 22.04, 24.04, and 26.04
Debian 12 and 13
AlmaLinux 8, 9, and 10
Rocky Linux 8, 9, and 10
CentOS Stream 9 and 10

Other operating systems, including Windows, have not been covered here. For those, check the network configuration against the floating IP guide for your system: AlmaLinux, CentOS, Debian, Ubuntu, or Windows.

Before making changes to your network configuration, it's always a good idea to take a backup.

In the examples below, the server's main IP address is 80.47.227.202 and the floating IP is 80.47.227.99. Replace them with your own addresses when you run the commands.

Network tab showing the main IP address and the attached floating IP on the public IPv4 interface

1. Prepare the operating system

When you create the new interface, it gets a new MAC address. On Ubuntu and Debian 13, the network configuration created by cloud-init identifies the public interface by its MAC address, so it no longer matches after the change and the server can come back without an IPv4 address.

To prevent this, change the configuration to identify the interface by its name instead. Do this now, while you can still connect over SSH using the original IP address.

Make a backup copy of the netplan configuration file.

sudo cp /etc/netplan/50-cloud-init.yaml /root/50-cloud-init.yaml.bak

Open the file in a text editor.
```
sudo nano /etc/netplan/50-cloud-init.yaml
```
If the file starts with a comment saying that changes to it will not persist across a reboot, you can still make this change. On UpCloud Cloud Servers, cloud-init only writes this file when the server is first set up, not on every boot, so your change stays in place across restarts.
Find the eth0 section near the start of the file. It looks like the example below, with your server's MAC address.
```
network:
  version: 2
  ethernets:
    eth0:
      match:
        macaddress: "16:44:a3:20:10:42"
      dhcp4: true
      set-name: "eth0"
```
Replace the macaddress line with name: "eth0" and delete the set-name: "eth0" line. Leave the other interfaces as they are. The start of the file should then look like this.
```
network:
  version: 2
  ethernets:
    eth0:
      match:
        name: "eth0"
      dhcp4: true
```
Save the file and exit the editor.
Apply the change with netplan try.
```
sudo netplan try
```
You might see warnings that the permissions of /etc/netplan/99-floating-ip.yaml are too open. They do not affect this change.
Press Enter when asked to keep the new settings. If you do not confirm before the timeout shown on screen, for example because your SSH connection dropped, netplan restores the previous network settings on the running server, but your edited file stays in place. In that case, restore the backup and then repeat steps 2 to 4.
```
sudo cp /root/50-cloud-init.yaml.bak /etc/netplan/50-cloud-init.yaml
```
Do not shut down the server until netplan try has accepted the change and the next step shows the main IP address.
Check that the server still has its main IP address.
```
ip addr show eth0
```

Debian 12: No preparation is needed.

Debian 13:

Make a backup copy of the netplan configuration file.

sudo cp /etc/netplan/50-cloud-init.yaml /root/50-cloud-init.yaml.bak

Open the file in a text editor.
```
sudo nano /etc/netplan/50-cloud-init.yaml
```
If the file starts with a comment saying that changes to it will not persist across a reboot, you can still make this change. On UpCloud Cloud Servers, cloud-init only writes this file when the server is first set up, not on every boot, so your change stays in place across restarts.
Find the eth0 section near the start of the file. It looks like the example below, with your server's MAC address.
```
network:
  version: 2
  ethernets:
    eth0:
      match:
        macaddress: "16:44:a3:20:10:42"
      dhcp4: true
      set-name: "eth0"
```
Replace the macaddress line with name: "eth0" and delete the set-name: "eth0" line. Leave the other interfaces as they are. The start of the file should then look like this.
```
network:
  version: 2
  ethernets:
    eth0:
      match:
        name: "eth0"
      dhcp4: true
```
Save the file and exit the editor.
Apply the change with netplan try.
```
sudo netplan try
```
You might see warnings that the permissions of /etc/netplan/99-floating-ip.yaml are too open. They do not affect this change.
Press Enter when asked to keep the new settings. If you do not confirm before the timeout shown on screen, for example because your SSH connection dropped, netplan restores the previous network settings on the running server, but your edited file stays in place. In that case, restore the backup and then repeat steps 2 to 4.
```
sudo cp /root/50-cloud-init.yaml.bak /etc/netplan/50-cloud-init.yaml
```
Do not shut down the server until netplan try has accepted the change and the next step shows the main IP address.
Check that the server still has its main IP address.
```
ip addr show eth0
```

2. Shut down your server

Shut down the server. You can do this from within the server itself, or in the Control Panel by going to your server and clicking Shut down.

3. Delete the public IPv4 interface

Go to the server's Network tab and find the Public IPv4 interface that has both the main IP address and the floating IP. Note down its interface index. You need it in step 4.

Then click the delete button for that interface.

Public IPv4 interface with its index and the delete button

The confirmation dialog lists both addresses with their release policies. Check that the main IP address shows Release (will be deleted) and the floating IP shows Keep (Detached Floating IP), then click Delete.

If either address shows a different release policy, click Cancel and change it before you continue. On the Network tab, click the edit button next to the address, set Release policy to Release for the main IP address or Keep for the floating IP, and click Save. Then delete the interface again.

Delete network interface dialog showing Release for the main IP and Keep for the floating IP

The main IP address is now deleted, and the floating IP is detached from the server and kept in your account. You can see it on the Floating IPs page under Network, where it is shown as "(detached)".

Floating IP shown as detached in the Floating IPs list

4. Create a new interface with the floating IP

On the server's Network tab, click Create interface and select Public network interface.

Create interface menu with Public network interface option

Keep Public IPv4 selected as the address type. Open the IP address dropdown and select your floating IP.

IP address dropdown listing the detached floating IP

In the Index field, enter the interface index you noted in step 3, then click Create.

Create public interface dialog with the floating IP and index 1 selected

The floating IP is now the IP address of the new public IPv4 interface. It is no longer marked as a floating IP on the Network tab.

Network tab showing the floating IP as the address of the new public IPv4 interface

5. Start your server

Start the server from the Control Panel. When it has booted, connect to it over SSH using the floating IP address, which is now the server's main IP address. Replace the address with your floating IP.

ssh [email protected]

Outgoing connections from the server now also use this address.

If you cannot connect, log in with the web console and check the network configuration.

6. Remove the old floating IP configuration

The static configuration you added when you set up the floating IP is no longer needed, because the server now gets the address automatically. Remove it and restart the server.

If you configured the floating IP differently from the setups below, remove the static configuration for the old floating IP address.

This applies if you added the floating IP in a separate netplan file as described in How to configure Floating IP on Ubuntu.

Delete the file and restart the server.

sudo rm /etc/netplan/99-floating-ip.yaml
sudo reboot

Debian 12

This applies if you added the floating IP as described in How to configure Floating IP on Debian.

Open the network configuration file.

sudo nano /etc/network/interfaces.d/50-cloud-init

Delete the block you added for the floating IP, for example:

auto eth0:1
iface eth0:1 inet static
address 80.47.227.99
netmask 255.255.255.255

Save the file, exit the editor, and restart the server.

sudo reboot

Debian 13

This applies if you added the floating IP in a separate netplan file, such as /etc/netplan/99-floating-ip.yaml.

Delete the file and restart the server.

sudo rm /etc/netplan/99-floating-ip.yaml
sudo reboot

AlmaLinux 8

This applies if you added the floating IP to the System eth0 connection with nmcli, as described in Add Floating IP on AlmaLinux 9.

Important: Do not delete the System eth0 connection. On AlmaLinux 8 it is still the active connection for the public interface after the change.

Remove the floating IP address from the connection, replacing the address with your floating IP, apply the change, and restart the server.

sudo nmcli con mod "System eth0" -ipv4.addresses "80.47.227.99/32"
sudo nmcli con up "System eth0"
sudo reboot

AlmaLinux 9

This applies if you added the floating IP to the System eth0 connection with nmcli, as described in Add Floating IP on AlmaLinux 9.

After the change, System eth0 is no longer used, because it is tied to the old MAC address. The server uses a connection named eth0 instead. Delete the old connection and restart the server.

sudo nmcli con delete "System eth0"
sudo reboot

AlmaLinux 10

This applies if you followed Add Floating IP on AlmaLinux 9 using the connection name cloud-init eth0, because the System eth0 connection in that guide does not exist on AlmaLinux 10.

After the change, cloud-init eth0 is no longer used, because it is tied to the old MAC address. The server uses a connection named eth0 instead. Delete the old connection and restart the server.

sudo nmcli con delete "cloud-init eth0"
sudo reboot

Rocky Linux 8

This applies if you added the floating IP to the System eth0 connection with nmcli, as described in Add Floating IP on AlmaLinux 9.

Important: Do not delete the System eth0 connection. On Rocky Linux 8 it is still the active connection for the public interface after the change.

Remove the floating IP address from the connection, replacing the address with your floating IP, apply the change, and restart the server.

sudo nmcli con mod "System eth0" -ipv4.addresses "80.47.227.99/32"
sudo nmcli con up "System eth0"
sudo reboot

Rocky Linux 9

This applies if you added the floating IP to the System eth0 connection with nmcli, as described in Add Floating IP on AlmaLinux 9.

After the change, System eth0 is no longer used, because it is tied to the old MAC address. The server uses a connection named eth0 instead. Delete the old connection and restart the server.

sudo nmcli con delete "System eth0"
sudo reboot

Rocky Linux 10

This applies if you followed Add Floating IP on AlmaLinux 9 using the connection name cloud-init eth0, because the System eth0 connection in that guide does not exist on Rocky Linux 10.

After the change, cloud-init eth0 is no longer used, because it is tied to the old MAC address. The server uses a connection named eth0 instead. Delete the old connection and restart the server.

sudo nmcli con delete "cloud-init eth0"
sudo reboot

CentOS Stream 9

This applies if you added the floating IP to the System eth0 connection with nmcli, as described in Add Floating IP on AlmaLinux 9.

Important: Do not delete the System eth0 connection. On CentOS Stream 9 it is still the active connection for the public interface after the change.

Remove the floating IP address from the connection, replacing the address with your floating IP, apply the change, and restart the server.

sudo nmcli con mod "System eth0" -ipv4.addresses "80.47.227.99/32"
sudo nmcli con up "System eth0"
sudo reboot

If you instead added the floating IP in an ifcfg-eth0:1 file, as described in Configure Floating IP on CentOS, delete that file, reload the connections, and restart the server. Do not delete System eth0 in this case either.

sudo rm /etc/sysconfig/network-scripts/ifcfg-eth0:1
sudo nmcli con reload
sudo reboot

CentOS Stream 10

On CentOS Stream 10, neither the ifcfg-eth0 file from Configure Floating IP on CentOS nor the System eth0 connection from Add Floating IP on AlmaLinux 9 exists. This applies if you followed the AlmaLinux 9 guide using the connection name cloud-init eth0.

After the change, cloud-init eth0 is no longer used, because it is tied to the old MAC address. The server uses a connection named eth0 instead. Delete the old connection and restart the server.

sudo nmcli con delete "cloud-init eth0"
sudo reboot

After the restart, connect to the server using the floating IP address again and check that the interface only has the new main IP address.

ip addr show eth0

Next steps

Your floating IP is now the server's main IP address. If other systems still refer to the old IP address, such as DNS records or firewall rules, update them to use the new address.

If you later want to move this address to another server, convert it back to a floating IP by following Converting a server IP address to a floating IP address. If you delete the server, the address stays in your account as a detached floating IP. Delete it separately if you no longer need it. For more information about floating IPs, see our guide on managing floating IP addresses.

Contributed by: Samir Haliru

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