First question: Do the devices have IP addresses internal to your LAN?
For example, my computer’s IPv4 address is 192.168.1.210. That IP address is assigned by the router (e.g. 192.168.1.1).
Here’s a list of private network IP address ranges:
Here’s what the first few IP addresses look like on my network

By the way, I can’t have 300 IP addresses on my LAN because it is configured to have no more than the usual 255. So is their really 300?