Some app servers in an SDM Advanced Availability implementation receive AHD04042 login time out error when trying to login to SDM with errors similar to below filling the stdlogs:
pdm_rfbroker_nxd 604 SIGNIFICANT rfbroker.c 401 Waited 1069378 seconds for background online notification.
Also, when failing over from Background server to Standby server, the demoted server may not shut itself down.
One potential cause for this is a DNS misconfiguration. The standard logs will show references to an incorrect IP.
Remove the incorrect IP reference from the DNS and restart the servers. This should resolve the login time out is as well as the issue with the demoted server not shutting down.