SQL Server access issue

You need to check your SSL and TLS settings.

Check out this KB 3135244. The settings between the client and server should be somewhat consistent (i.e. if the server only allows 1.2 and the client only supports 1.0 I think you might run into issues). Also read through the known issues on that page

Updating to a build that supports TLS 1.2 might resolve your issue.

The accepted answer here did not solve my issue.

I had the same issue and was able to resolve it by making sure that the cipher suites and key exchanges were the same on the client(web server) and db server.

You can find a more detailed message in the windows event viewer system log:

I used IISCrypto to enable the required ciphers:

I have the same issue and found it to be related to the certificate not being correct on the sql server.