Why is the USB interface not visible at WIN10?

What can I do if if the USB interface of a series ZS or NL device is not visible as Virtual COM Port anymore in the Windows Device Manager after the system was ported from an XP to a Windows 7 or Windows 10 operating system?

• For NL and ZS series devices delivered before June 2014 the USB driver of H&H’s homepage has to be used. In other cases, the most up-to-date driver from FTDI has to be used (https://www.ftdichip.com/Drivers/VCP.htm).

• The H&H USB driver is not signed and only tested with Windows 7 (64  Bit) and Windows 10. Please contact the H&H support if there are still problems with the USB driver.

• The date code of delivery is coded in the last four characters of the load’s serial number (MMYY).