Change OS on Vultr instance
WARNING! Make a backup. Do not proceed further without backups. This is a destructive process where all the data on the server will be wiped out and data loss.
Vultr instance OS from the Vultr account control panel using the below steps.
Servers > Click on the Vultr Cloud Compute > Settings > Change OS > Select the OS > Click on Change OS.
output
Currently Installed: Ubuntu 18.04 LTS x64
Your new operating system is now installing.
The advantage here is that the IP address stays the same.
Note
However, this is a destructive process where all the data on the server will be wiped out.