Similar experience here after seven networks with MR42 (and some MR86) APs upgraded from MR 29.5.1 to MR 30.7 overnight.   We have various SSIDs configured across the seven networks in question.   We experienced at least two networks where an SSID configured for Identity PSK with RADIUS did not permit clients to move past the association step.   Event logs showed clients attempting to associate but never moving to the wpa_auth step. After not too long, associations from clients on the SSID in question were failing with reason code 17.   Finding this thread (and another thread on Reddit), we disabled client balancing and the symptoms subsided.   The remaining networks that have an SSID configured for Identity PSK with RADIUS do not currently have active clients that would be attempting to use that SSID, so we don't yet know if they're affected.   Like others, we've opened a case with Meraki support to report the issue and seek more details. ... View more