Is there any way to suspend/stop a TM server so that it should not serve new forms to online users? but it should let users to finish and submit existing open forms, so once all open forms are submitted and there are no more new forms out there from TM server, this will give us a safe window where we can maintain the TM server (e.g. re-starting Avoka Transaction Service etc..) without impacting live user's experience.
Ideally these type of maintenance windows are managed by publishing outage notifications and not based on type of uses (new vs in-progress forms).
TM server has ability to put entire 'Space' or 'Portal' in maintenance mode to stop receiving new and existing form render and submission requests. This maintenance mode will stop all incoming traffic. There isn't anything that let's you filter traffic based on new vs existing form basis.