1. You need to have a current version of SQL Native Client 11. The version of the SQL Native Client that’s included with current releases is current and has been for some time now. The install has been updated to not only check to see if the SQL Native Client 11 is installed, but also check the version installed and update it if necessary. This happens during the startup of the install so it will be in place before any SQL related activities take place. The operator will be notified of this with a Message Box.
2. TLS 1.2 support needs to be turned on in the client machine. This applies even if the client is the server machine. If you have the TLS 1.2 client protocol turned off you can’t connect to a server that limits support to TLS 1.2 only. This is normally controlled with some registry settings. If you’re having trouble connecting you can now add the -TLS12 command line switch to the install (188.8.131.52 +) next release. This will automatically check those registry settings during the startup phase of the install and if TLS 1.2 was not enabled it will set the registry settings for you and prompt you to reboot.
When testing all this out found this helpful free utility you may find useful. Run it on the server and/or client. It will show you what settings are currently enabled/disabled and allow you to modify them. Changing most of these settings will require a reboot. I would recommend only changing the TLS settings.