Auth issues with IMAP Backend // Dovecot

I’m able to access the /Microsoft-Server-ActiveSync URL however regardless what is entered as username logs show user as Unknown. Backend is IMAP via Dovecot.

Any idea?

05/03/2018 12:01:31 [ 3827] [DEBUG] [unknown] [] -------- Start
05/03/2018 12:01:31 [ 3827] [DEBUG] [unknown] [] cmd='' devType='' devId='' getUser='unknown' from='1.1.1.1' version='2.3.9+0' method='GET'
05/03/2018 12:01:31 [ 3827] [ INFO] [unknown] [] AuthenticationRequiredException: Access denied. Please send authorisation information - code: 0 - file: /usr/share/z-push/index.php:56
05/03/2018 12:01:31 [ 3827] [ INFO] [unknown] [] User-agent: 'unknown'
05/03/2018 12:01:31 [ 3827] [FATAL] [unknown] [] Exception: (AuthenticationRequiredException) - Access denied. Please send authorisation information
05/03/2018 12:01:31 [ 3827] [DEBUG] [unknown] [] ZPush::PrintZPushLegal()
05/03/2018 12:01:31 [ 3827] [DEBUG] [unknown] [] TopCollector(): Initialized mutexid Resource id #40 and memid Resource id #41.
05/03/2018 12:01:31 [ 3827] [DEBUG] [unknown] [] TopCollector initialised with IPC provider 'IpcSharedMemoryProvider' with type '20'
05/03/2018 12:01:31 [ 3827] [ INFO] [unknown] [] cmd='' memory='2.24 MiB/2.50 MiB' time='0.02s' devType='' devId='' getUser='unknown' from='1.1.1.1' idle='0s' version='2.3.9+0' method='GET' httpcode='401'
05/03/2018 12:01:31 [ 3827] [DEBUG] [unknown] [] -------- End

It seems as all the GET parameters are missing. No command, devtype, devid etc.
How did you setup your webserver? Are the GET parameters being passed to the script?

Thanks that got me in the right direction. It was due to PHP set as FastCGI.