I'm using several AirPort Extremes to create a wireless network for a large amount of devices. One AirPort is advertised to support 50 devices, so I'm using 4 AirPorts currently for 200 devices.
My setup consists of 1 AirPort in DHCP and NAT mode, and the remaining AirPorts in Bridge mode.
Now, I'd like to extend the network capacity to 400-ish devices.
One issue I see is that AirPort Utility only supports setting DHCP ranges within a /24 subnet, meaning that there is a maximum of around 250 devices possible.
It is important that all devices share the same subnet, because the used application requires UDP broadcasts to communicate with other peers.
It is also important that roaming (i.e. moving around in the room and reconnecting to other base stations without disconnects) is possible. This works fine with my 4 AirPort setup so far.
What is the preferred way to create a larger than default subnet (e.g. /23) using Apple AirPort Extreme?
Best Answer
The maximum number of addresses you can have on a /24 subnet is 256, so you are right on target with having 250 or so. This includes the IP for the gateway, and the broadcast, so, you are now down to 254.
For example, using a Class C subnet with a mask of /24 your range will be
This is not a limitation of the Airport, but of the IP network itself. What you can do is change the netmask so it will allow more IP's within the given subnet:
Will allow a subnet with up to 508 clients.
Totally opinionated section....
If you are managing this many devices/clients on a network, Airport is NOT something I would use. I would look at getting "Enterprise Grade" networking gear like Ubiquiti UniFi Pro with much better management capabilities. They even have a "lite" version in which the all the controller software and config is centralized.