This document https://msdn.microsoft.com/library/dn683916(v=crm.6).aspx describes the connectivity requirements for CRM in various configurations.
Three ports which must be enabled on the CRM server are:
- 80 for incoming web access using http
- 443 for incoming web access using https
- 808 for the CRM SDK Listener
A symptom of no access on port 808 is that FetchXML based reports do not work.
Here is something that I hadn't seen before, the Performance Center. Courtesy of a post by PowerObjects, type CTRL+SHIFT+q to reveal the Performance Center. The first time you do this, click Enable to start tracking performance and then Close.
Then after you open a record call up the Performance Center again (CTRL+SHIFT+q) tosee how long each part of the form load took.
Click Disable in the Performance Center to turn off performance tracking.
Not all updates for CRM 2015 are available for all components. In particular the Update 1.0 series (which introduced functional changes) is not available for On-Premises server. However, Update 1.x is available for some of the other components.
Note that even though the Microsoft KB article references CRM Online in Update 1.0, you can still apply Update 1.0 (and later) to the CRM for Outlook Client if connected to an On-Premises server.