Symptoms
When you try to connect to a Microsoft Exchange Server 2016 server installed on a Windows Server 2016 computer by using Mozilla Firefox or Google Chrome, you receive an error message. The error messages are as follows.
Chrome: ERR_SPDY_INADEQUATE_TRANSPORT_SECURITY
Firefox: NS_ERROR_NET_INADEQUATE_SECURITY
Resolution
Microsoft acknowledges this is an issue with Exchange 2016. It will be addressed in Cumulative Update 6 for Exchange Server 2016.