There are two criteria which could potentially limit the number of viewers that can watch a live internal stream via a single DEVOS server:
1. CPU usage on the server
2. The network interface (NIC) that the server uses to connect to the network
CPU Limitations:
The amount of server CPU that a live stream delivery will use depends on the bitrate of the encoded stream. The higher the bitrate, the more CPU will be required to deliver the live stream since the server is delivering more bits of information per second. Based on our testing, a single DEVOS server can deliver a live stream to anywhere between 1,000 - 2,000 simultaneous viewers, or about 1,500 simultaneous viewers on average.
Network Interface Limitations:
A single DEVOS server is configured with two individual 1 Gbps (gigabits per second) network interface cards (NICs). With a standard installation, DEVOS servers are only configured to use one NIC at a time. With this configuration, the most bandwidth a DEVOS server can deliver at one time is 1 Gbps. If a live stream is encoded at 500 Kbps, then the server can deliver the live stream to no more than about 2,097 simultaneous viewers (1,048,576 bits per second max / 500 Kbps stream). In actuality, a server NIC cannot realistically deliver to 100% capacity. A good rule of thumb is to expect a maximum delivery rate of about 85% of the 1 Gbps. Based on that same 500 Kbps live stream, that brings the total simultaneous viewer maximum down to about 1,782.
It's possible to configure the Windows Server operating system on the DEVOS server to use both NICs, and therefore theoretically double the outbound deliverable bandwidth speed, but as mentioned earlier, this would likely result in the CPU usage maximum capability of the server being reached before the full NIC speed capability was reached.