If you’re in a conference as Supervisor and you see some video packet lost in some users, you can arrange a simply test for those to verify their connection.
Open the remote user audio control window (from a PC) by the main horizontal menu -> Windows -> Remote user audio control and select a user in the column at the right. Then click on the yellow box at the bottom right (2) and in the report area (3) will appears the report of connection. If the report is bad, the remote user needs to change connection (for example, using a LAN cable instead of a WI-FI connection, or reaching another point with 3G connection, or changing his audio/video quality to a only audio mode.).
PC: Remote audio control window