How to correctly save data to the MySQL database in UTF-16LE encoding received through the server package?

Question

Unicode

The bottom line is:
Receive through a package from the client - enter for example 123456 Then I write it to the database in the form of a string - how this value was saved in the database when entering the second code: 123456 in the client interface gives me a verification error. That the entered data does not match the data in the database. How can I solve this coding issue? key = new String(readB(48), "UTF-16LE");