Currently, as of Connect 9.3.1, Adobe Connect hosted Seminars may launch on regular Connect Meeting server instead of their designated Webinar servers. If Seminar preparation keeps the Seminar room open for an extended period just prior to to the actual Seminar itself, the Seminar may remain on a Meeting server that is not rated for a large capacity Seminar. Simple precautions will avoid this from happening.
In order to avoid this, on the day of the scheduled Webinar, be sure to open the Seminar room only 30 minutes prior to the start of the Seminar session. By opening the Seminar earlier and keeping it open for final editing right up to the start of the Seminar session, you can lock the seminar onto a regular Connect Meeting server rather than on a Webinar server designed for large capacity sessions. While you can certainly spend as much time as needed to prepare your seminar room in advance of the actual session, you should close the Seminar room for at least seven minutes prior to the actual scheduled Seminar session. Seven minutes is the time it takes the Seminar room to process garbage collection from editing and preparation activities before opening up for the real event.
Adobe is looking at ways to automate the transition from a regular Meeting server to a Webinar server with an eye toward future release. In the interim, just be sure to time your final Seminar preparation to allow for transition to a Webinar server where large Seminar concurrency is supported with robustness.