Why does my NDI connection stay active once the source is offline?

NDI as a protocol is designed for easy and seamless connections. However, as NDI is also designed to be used across a wide variety of user-implemented networks, the video stream may go offline for to a number of reasons i.e. a pulled cord, lost power, user-caused 'stop' on the device, etc.

When a connection is suddenly lost, NDI will handle that as being 'improperly closed'. The receiving end will attempt to keep the sending NDI IP and port number open and available for a number of minutes in case the issue is resolved, so the user won't need to re-discover the NDI source. By default, it's a 75 minute timeout. If there's been no re-advertisement to renew the time to live, it'll be removed after 75 minutes. Due to this, NDI is designed to hold onto the last frame that was sent as a still within the receiver's buffer and no other image or video signal can use that same IP and Port.