Skype for Business Server ACP MCU failed multiple successive attempts to bridge VOIP and PSTN conferences for one or more ACP partners.
Possible causes are connectivity issues between the Mediation Server and the ACP partners.
Check and make sure there are no connectivity issues with the partner network(s) for the partner(s) which are shown as failed below. Also, check to see that the ACP partner(s) indicated as having failures are not out of service. Check previous events from ACP MCU component for more details on the failures.