Setting up rule to block internet for range of IP addresses
I have the latest Archer C9 AC1900 Wireless router and I want to be able to set up a rule where all non-reserved IP addresses are blocked from accessing the internet. A little background is that I currently work on a Navy base on a tiny island. The internet is limited to 28GB or 50GB per month with upload and download combined. I have the 28GB plan, which is $175/month. I also have a server that has 16TB of movies, music, TV shows, books, etc that I would like for others in the barracks to be able to access.
Due to the limitations on the internet, I need a way to block all IP addresses except those I have reserved for my electronics, so that people can then log in to the router and access the server. I previously had an older version of the C9 (or maybe it was the C8) that allowed me to set up a rule to block a range IP addresses from accessing the internet, but still allowed them to access anything else on the LAN. The problem I am having is that I can't find a way to set up any rule, or limit internet access in any way, for a range of IP addresses.
Can anybody provide me with a way to do this so that I can provide people with access to the server, yet keep them from accessing my internet account?