Information
Uncomplicated Firewall (UFW) is a program for managing a netfilter firewall designed to be easy to use.
Uses a command-line interface consisting of a small number of simple commands
Uses iptables for configuration
Rationale:
Running iptables.persistent with ufw enabled may lead to conflict and unexpected results.
Solution
Run one of the following commands to either remove ufw or stop and mask ufw
Run the following command to remove ufw:
# apt purge ufw
OR
Run the following commands to disable ufw:
# ufw disable