High STUN delay

connectivitynetwork

The time to receive the first STUN candidate was too long. This may slow down connection setup.

Description

During ICE gathering, the browser discovers candidates (host, server reflexive from STUN, and relay from TURN). The time from when gathering starts to when the first STUN (server reflexive) candidate appears reflects how quickly the STUN server responds.

When this delay is too long, it could slow down the connection setup and can indicate network latency to the STUN server or an overloaded STUN server.

What do we do here?

We compute the duration from the first ICE gathering state change to the timestamp of the first STUN candidate in the peer connection. If this duration exceeds 500 ms, we mark it as an observation.