If you are using storage zone controller 3.4 you may see the following error appearing in Windows logs
An TLS 1.2 connection request was received from a remote client application, but none of the cipher suites supported by the client application are supported by the server. The SSL connection request has failed
This will happen if your IIS server has TLS 1.2 enabled (on Windows 2012r2 TLS 1.2 is enabled by default).
Sharefile storage zone controller 3.4 does not support TLS 1.2
Options are:
Upgrade to sharefile storage zone controller to v4.0 or later - Legacy Documentation
Disable TLS 1.2 on the Windows server - instructions available here: TLS-SSL Settings | Microsoft Learn