Information
nftables is a subsystem of the Linux kernel providing filtering and classification of network packets/datagrams/frames.
The nftables service reads the /etc/nftables.conf file for a nftables file or files to include in the nftables ruleset.
A nftables ruleset containing the input, forward, and output base chains allow network traffic to be filtered.
Rationale:
Changes made to nftables ruleset only affect the live system, you will also need to configure the nftables ruleset to apply on boot
Solution
Edit the /etc/nftables.conf file and un-comment or add a line with include <Absolute path to nftables rules file> for each nftables file you want included in the nftables ruleset on boot
Example:
# vi /etc/nftables.conf
Add the line:
include '/etc/nftables.rules'