The China Premium network is a dedicated network that was setup to enable higher-quality access for Teams and other services for users based in China, using the public internet. Be sure to review the following for more information: https://aka.ms/tuneChina
Microsoft Teams is taking an ongoing maintenance window to improve the China Premium network service. More information is available in MC post MC422140, tenant Admins can click directly on that link to review.
The maintenance window started on 24th August 2022 and is planned to complete by 30th, September 2022, UTC. During this time period any users in China who join a Teams meeting hosted in another data center outside the Asia Pacific region will use China's regular cross-border network service. This could result in poor quality for audio, video, and screen sharing.
Users in China can attempt to work around this situation by being the first person or client to join a given meeting, which ensures the meeting will be hosted in Asia Pacific regional data centers.
However, if China users did not start or be first one to join the meeting, and the meeting includes users from other regions, they may experience poor quality for audio, video and screen sharing. Most likely the meeting is hosted in another region. In this scenario China users are connecting through the public Internet, which might be impacted by cross-border network congestion.
IT admins can confirm this scenario by validating the meeting's data center location with the following steps. China users experiencing poor quality in a meeting that has already started can try turning off incoming video, disabling their own video, or dialing into the meeting via phone if available to improve performance.
During the meeting
Collect the Wireshark trace and filter ‘UDP.port==3479’.