Not possible to add a new IP address in Plesk on a Cloud-based server: This IP address is not configured properly

Symptoms

1. Attempting to add an IP address via Plesk > Tools & Settings > IP addresses results into the following error:

PLESK_WARN: This IP address is not configured properly. Repair

2. Clicking repair doesn't resolve the issue and does not report any additional errors as well.

3. A new IP address is not added to the network interface:

# ip a
ens6: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
inet 203.0.113.2  netmask 255.255.255.255  broadcast 0.0.0.0
(...)

Note: 203.0.113.2 is an old IP address here.

4. The /etc/netplan/10-plesk.yaml file is configured correctly and contains the new IP address:

# network:
 version: 2
   renderer: networkd
ethernets:
ens6:
 addresses:
   - 203.0.113.1/32

5. The ip addr add 203.0.113.1/32 dev ens6 command doesn't add an IP address to the interface.

6. The plesk bin ipmanage --repair 203.0.113.1 command solves the issue temporarily.

7. The server is cloud-based.

Cause

Cloud servers have different configurations for the network interfaces which are configured in a non-default way (for example, renderer option is set to networkd)

Resolution

1. Log into the server via SSH.

2. Adjust the configuration files in /etc/cloud/cloud.cfg.d/99_custom_networking.cfg and /etc/cloud/cloud.cfg.d/99_ionos.cfg so that they have networkd next to the renderer: . In the end, the should looks like this for instance:

CONFIG_TEXT: network:
version: 2
renderer: networkd
ethernets:
all-en:
match:
name: "en*"
dhcp4: true
dhcp6: true

3. Apply the configuration by using this command:

# plesk sbin ifmng -s systemd-networkd

4. If the IP address is not added automatically to the interfaces, try to re-add it once more via Plesk > Tools & Settings > IP Addresses.

Note: The configuration file might differ depending on the cloud provider. Consult cloud provider documentation for more information.