Milestone 2025 R2 Webrtc Stream Encrypted Alert

When connecting to a milestone camera via WebRtc the stream will cut out after a few minutes. When looking at a network capture we noticed that the milestone endpoint was sending an Encrypted Alert before the stream was cut off.

Searching encrypted alerts I saw:

What It Means

  • Encrypted Payload: Packet analyzers like Wireshark show “Encrypted Alert” because the content is protected by symmetric encryption keys established during the handshake; the analyzer cannot read the plaintext without the session keys.

  • Structure: The alert contains two bytes—one showing the severity (warning or fatal) and another identifying the specific condition. [1, 2, 3]

Common Causes

  • Session Closure: Most frequently, it is a normal close_notify message indicating that one side is shutting down the session cleanly.

Please advise how we can move forward determining the reason why Milestone VMS is ending the webrtc stream.