Error code Connectivity_ICEWarn 0x80020 and Connectivity_ICEWarnEx 0x90

These two entries are not “hard errors.” They are ICE (Interactive Connectivity Establishment) warnings related to how Teams tried to establish media connectivity for the call.

What they mean in practice:

Connectivity_ICEWarn (0x80020)
This means ICE detected a connectivity problem during candidate testing.
Teams tried multiple network paths (UDP, TCP, relay, etc.), and at least one preferred path failed.

Common causes:

Firewall or NAT blocking UDP

Strict NAT type

Port restrictions

Packet loss or unstable network

Connectivity_ICEWarnEx (0x9000)
This is an extended version of the same warning, giving more internal detail.
It usually indicates that Teams had to fall back to a less optimal path (for example, from direct UDP to TCP or relay).

How to interpret them:

The call did not necessarily fail.

Media likely connected, but not in the best possible way.

Quality might be lower (higher latency, more jitter, possible audio/video issues).

What to check:

Make sure UDP 3478–3481 and media ports are open as per Microsoft Teams network requirements

Check firewall/NAT behavior

Verify no SSL inspection or traffic shaping is breaking real-time traffic

Compare with Call Quality Dashboard (CQD) for packet loss, jitter, and latency

Summary:
These codes mean “Teams struggled to find the best network path and had to use a fallback.” They explain why a call might have reduced quality, not why it completely failed.