We have a user in our organization that is unable to access our SQL Server databases. All other users are able to access the databases. They are authenticating in using operating system authentication. I had the person try connecting from my machine and she was able to get in, so we have ruled out the issue being due to permissions. We also confirmed that she has the proper SQL Server Client and ODBC driver installed. Our databases are running under SQL Server 14 and the driver she is using is Microsoft ODBC Driver 17 for SQL Server. She also has the SQL Server 2012 Native Client installed. I have read through the documentation and we appear to have everything installed that needs to be. She did have the driver installed on her machine prior to running the ArcMap installation. She has other applications that use the driver. The only other thing I can think of is a setting not being correct in the Registry. Is there anything else that might be causing the error? We have been instructed to rerun the Desktop installation if we cannot resolve the issue but I am afraid that might not fix the error. The error returned by ArcMap states "Failure to access the DBMS server".
Can you check to see if the the port being used for SQL Server is open on the client machine? I think that the default port is 1433.
Try to TELNET from the client machine with the issues to the SQL Machine. https://www.acronis.com/en-us/articles/telnet/
Another option is to install SQL Server Management Studio and try to make an OS connection to the SQL instance; Download SQL Server Management Studio (SSMS) - SQL Server Management Studio (SSMS) | Microsoft Docs
If you installed the 64 bit ODBC, it also installs the 32 bit drivers.
We resolved the issue by uninstalling the ODBC driver and then reinstalling it. We originally tried to install the driver thinking it wasn't installed on the machine but received a message stating a newer version of ODBC Driver 17 was already installed. We installed a version we received from ESRI. Thanks for the helpful responses.