Different sporadic SQL Server errors First question on this SA but I feel my problem is more Database related than code related.

I have multiple Delphi Datasnap servers connecting to SQL Server 2012.
The SQL server has multiple databases (500+) which the different Database servers connect to. The SQL Server and the Application servers run on different VM's. Different users connect to these application servers and open connections to the databases. 

Since today we are getting different SQL errors on the servers, but no errors are seen on the SQL Server. These errors happen only sporadically for different users on the server in different databases. We are almost unable to reporoduce as this seems like a small % of the calls to the SQL server.

Example of errors we get are : 

[FireDAC][Phys][ODBC][Microsoft][SQL Server Native Client 11.0]TCP Provider: An existing connection was forcibly closed by the remote host.
[FireDAC][Phys][ODBC][Microsoft][SQL Server Native Client 11.0]SMux Provider: Physical connection is not usable [xFFFFFFFF].
[FireDAC][Phys][ODBC][Microsoft][SQL Server Native Client 11.0]Unable to complete login process due to delay in opening server connection.
[FireDAC][Phys][ODBC][sqlncli11.dll] SQL_ERROR


Googling these errors gives some results on Chimney settings but most of the results are older than 2012 and most are for SQL Server 2008.

Are there any suggestions on possible causes? Any other info you need?
(More like a Delphi problem to me)

In my case, it had to do with a recent reinstallation of Access.
Access MDAC not beeing compatible with sqlncli11.dll, this mean I had to rebuild the whole application.

If I get it right, Delphi compiled only the units that I modified, using (I don't even know why, as I don't use Access) the current MDAC and it collided with the old DCU that were compiled using the old MDAC.