Just installed the following firmware located on the Dahua website for my IPC-HFW5231E-Z5.
DH_IPC-HX5X3X-Rhea_EngSpnFrn_N_Stream3_V2.460.0000000.16.R.20170904
I noticed the camera did not return online after it self reboot at 3AM, but managed to get it back online. So, I went to Dahua site and their new firmware corrects this issue according to the documentation posted on the firmware corrections. So far the camera is working fine with no issues.\
Device Type IPC-HFW5231E-Z5
System Version 2.460.0000000.16.R, Build Date: 2017-09-04
WEB Version 3.2.1.491565
ONVIF Version 16.12(V2.4.0.485616)