@Alan

Welcome, thanks for the feedback.

You could do that, but your configuration is wrong. You need to learn about subnet masking. Your netmask would need to allow for all those clients to fit in the range. After that you could add all the subnets you want and need.

Another issue you will run into is broadcast storms with that many clients on the same network partition. This will be even worse if you are using wireless comms.

If you want to carry on then something like this should do the trick:

A subnet of 255.255.252.0 will yield = 192.168.16.1 – 192.168.19.254

No you can’t just start from .10.x because that subnet is in the middle of another one.

subnet 192.168.16.0 netmask 255.255.252.0 {
        option routers                        192.168.16.1;
        option subnet-mask              255.255.252.0;
        option domain-search            "tecmint.lan";
        option domain-name-servers      192.168.16.1;
        range   192.168.16.10   192.168.16.255;
        range   192.168.17.10   192.168.17.255;
        range   192.168.18.10   192.168.18.255;
        range   192.168.19.10   192.168.19.254;
}

It looks weird to most people but 192.168.16.255 is a usable address in this subnet. This will give you the first 10 IP address in each number range to be static if you want but maximises on usable address in the dhcp server.

I would also recommend looking into splitting this into 2 maybe 4 servers. DHCP works on a race. The first server to respond can issue the IP address. Therefore if one of your servers breaks, then the others can still service your clients.
People don’t like it when “the internet” breaks.