I am working on a dedicated WiFi network of real-time, IoT devices communicating with MQTT. Messages are very short, approximately 100 bytes. There will be at least 85 devices on the network.
IoT application is written in MicroPython and uses standard WiFi & MQTT libraries. There's nothing exotic. Each device gets an IP, and subscribes and publishes to two topics. Each device probably uses two IP sockets that always need to remain connected and open.
The MQTT server is local and there is no internet. Many devices will send their data at nearly the same time in response to an event. Events are spaced at least 15 seconds apart. Maximum message bursts will be under 20,000 bytes split between 85 devices.
The physical space is wide open. Most distant devices will be around 35 meters away. WiFi repeaters can be used as needed.
With a low-ball estimate of 500,000 Mbps WiFi capacity, bandwidth does not appear to be the problem. Without collisions, it would take 40ms to send that. Up to one second latency in sending messages is acceptable.
How many short-message IoT devices can reasonably be simultaneously connected to a modern WiFi router? Typical routers I'm looking at can support around 252 IP addresses in their DHCP table. Is it reasonable to push that limit with IOT devices? Is WiFi overhead for many simultaneous connections the biggest concern?