I initially had one Exchange 2013SP1 server (EX01)(running Mailbox/CAS roles) running on Windows 2012.
As we want to move to Windows 2012R2, I build two Windows 2012R2 servers and installed Exchange 2013SP1 on each one. Server MB01 hosts the MAILBOX role only and server CAS01 hosts the ClientAccess role only.
The installs all went ok, I have migrated the users (including arbitration etc) from EX01 to MB01 and reconfigured external access to come via CAS01.
Everything works fine... That is until I power off EX01
With EX01 powered off, I cannot access the ECP or OWA via CAS01 (either internally or externally).
I get the OWA login screen, but after a while I get a HTTP 500 Internal Server error. Full Outlook clients can still connect.
When EX01 is powered on again everything returns to normal.
I have tried re-creating the OWA & ECP virtual directories on CAS01 and MB01 but to no avail.
It appears that there is something in the config hard coded to use EX01 but I can't find it.
Many thanks in advance for any help
Steve