The official, Microsoft-supported tool for this task is Sysinternals SerialPortMon (also seen as serialmon ). It is designed for Windows 10 and Windows 11, with proper 64-bit drivers.
The way Windows handles I/O requests for COM and LPT ports has evolved significantly since the XP era. How to Run Portmon (The Workarounds) portmon windows 11
Searching for is a journey into the past. The classic tool, while beloved, is a technological dead end. It relied on driver models and 32-bit architectures that Microsoft wisely retired for security and stability. The official, Microsoft-supported tool for this task is