Finally think I've sorted it: The secondary in question had become disconnected from AD. I had to unregister it from the primary, clear the AD config, reconnect it to AD, then factory default it (it maintains it's IP config so it's OK), re-enter th...
I'm still seeing these 11051 errors on one of my secondaries ... seems similar to what grnetcomss was seeing. I corrected the ntp and timezone issues, but one ACS appliance does not appear to be doing any successful authentications and only logging ...
I also had this problem ... Found that a couple of the secondaries had wrong timezone and no NTP set. From the command line:config tntp server clock timezone Australia/BrisbaneYou then need to restart ACS.It's all good now ... Thanks for pointing m...