I had an issue that had me perplexed recently. Citrix Sharefile with a premise based Storage Zone, intermittently unable to upload files from inside and outside the company, several calls to Citrix and the networking teams resulted in no fix.
Using the IISCrypto tool apply best practices and reboot the storage zone controllers.
or follow these directions from Microsoft: https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2012-R2-and-2012/dn786418(v=ws.11)
you are welcome!