Have you checked the keychain on the server in identity preference of com.appple.servermgr ?
There should be a setting for preferred certificate to use with the services.
Maybe it got swapped by FMS install.
Thank you for your post!
A lot has been enhanced with FileMaker Server 15 security and SSL capabilities. The System Requirements for FileMaker Server 15 do not include OS X Server as a supported environment, so you may want to deploy on a dedicated environment. I am going to inquire about changes that may be causing this behavior. I'll report back once that information is available!
Thank you for your responses. Hopefully moving to a dedicated environment will be a last resort. I didn't see in system requirements where OS X Server was mentioned as not being compatible?
Perhaps this SSL diagnostics is helpful? Would this be remedied with trusted filemaker certs? Seems like the FileMaker Certificates (Filemaker Root Authority) override existing certs?
...now all Server accounts cannot log into their server accounts.
Could you elaborate on the above as far as what the Server Accounts are and where they are unable to log in?
Also, does the issue occur when SSL is disabled?
What is the reason for your focus on troubleshooting the SSL?
Just to give an update on this, after doing about 2 hours with Apple Enterprise Tech support and going through 3 levels of technicians trying to figure out FMS's effect on OS X Server and control of certificates, the end consensus was to just revert our server back to before we installed FMS 15 and the corresponding certificates and then purchase a dedicated iMac to run FMS 15. All is well now but it was a major headache.
We had never had problems running FMS on our OS X server in the past. I think FileMaker should make a point of clearly stating in the System requirements that FMS 15 is NOT compatible with OS X Server instead of just alluding to the fact that it "isn't listed as a supported environment." OS X Server is a separate application so saying that FMS 15 is compatible with OS X El Capitan 10.11 does not in any way preclude or warn against running the OS X Server app.