>>>Back to the story. I asked the IT to enable TLS 1.2. He said he did but the same error. I really don't know if he did or how he did it. So, I was trying to understand how to enable TLS 1.2 on a PC better before I ask the IT to let me connect to the PC. I also offered the IT to replace the ODBC driver with the newer, Native. But he wrote "Since everything works everywhere else, I don't want to change anything, just because of this PC"
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>>It may have to do with the version of the ODBC driver on that PC, that may not support TLS 1.2
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>It may. But the ODBC has not been changed; something else changed. And then the ODBC stopped connecting to the SQL server.

I've seen TLS becoming mandatory in a few places. I know I had to edit the connection in some places, but it's one of those things that are done not every year, so I have completely forgotten what it was. An FTP, PgSql, email or whichever connection. But TLS was the thing I had to add to make it work.

Check your ODBC driver's documentataion (ha! you don't know where it is! - neither do I), there may be just another clause to add to the connectstring to make this work.