Static IPv4/IPv6 Addresses - Debian 11

 Here's how to set both static IPv4 and IPv6 addressing on Debian 11. The new portions are outlined in italics.

First, edit /etc/network/interfaces

 1auto lo  
 2auto ens192  
 3iface lo inet loopback  
 4# The primary network interface  
 5allow-hotplug ens192  
 6iface ens192 inet static  
 7    address _**{{ ipv4.address }}**_  
 8    gateway _**{{ ipv4.gateway }}**_  
 9iface ens192 inet6 static  
10    address _**{{ ipv6.address }}**_  
11    gateway _**{{ ipv6.gateway }}**_  

Then, restart your networking stack:

1systemctl restart networking