Using a random non-default subnet increases security (slightly, and only through obscurity) by making it harder for a compromised device to perform automated attacks against, most often, your router. Typically they’re pretty simple scripts that just try to hit default ports on default IPs.
If someone is on the inside of your network you have much bigger issues. Having a random subnet won’t do anything as they can just look at the arp/ndp tables.
Why?
Using a random non-default subnet increases security (slightly, and only through obscurity) by making it harder for a compromised device to perform automated attacks against, most often, your router. Typically they’re pretty simple scripts that just try to hit default ports on default IPs.
That’s not how networking works
If someone is on the inside of your network you have much bigger issues. Having a random subnet won’t do anything as they can just look at the arp/ndp tables.