Main IP address resets after a server reboot

Symptoms

• Even if a specific IP address has been set as the main one, it reverts to the previous one after a server reboot.
• The main IP address was added to the server through Plesk, and its config is in /etc/netplan/10-plesk.yaml.

Cause

This is caused by race conditions at server boot. The main IP address hasn't been assigned to the network interface when Plesk looks for it, so it can't find it.

Resolution

To fix the issue, the system should be configured to assign the IP address first, so Plesk can detect it in time. One possible way to do this is to set the IP address in the main configuration file, instead of /etc/netplan/10-plesk.yaml

Note: The following instructions are for a server running netplan. Exact steps, network interfaces, and configuration files may differ. Contact a network administrator for help if unsure.

1. Turn the desired IP address into the main one once again: How to change the main (primary) IP address in Plesk for Linux

2. Get the contents from /etc/netplan/10-plesk.yaml and note down the IP address' interface (in this case, ens5)

   # cat /etc/netplan/00-installer-config.yaml
   ethernets:
   ens5:
   addresses:
   - 203.0.113.2/32

3. Edit the main configuration file (in this example, 00-installer-config.yaml)

   # vi /etc/netplan/00-installer-config.yaml

4. Enter the IP address in the appropriate interface. For example:

   network:
   ethernets:
   ens5:
   dhcp4: true
   dhcp6: true
   match:
   macaddress: 02:39:9e:56:d2:09
   set-name: ens5
   addresses:
   - 203.0.113.2/32
   
   version: 2

5. Move /etc/netplan/10-plesk.yaml to some other location on the server as a backup

   # mv /etc/netplan/10-plesk.yaml /root/