Greetings Steve,
If you are referring to the alpha numeric name of the device found in the upper right hand corner of the MF Scan Utility, that's is not a serial number. It's a MAC address (truncated) which is either the Ethernet or WiFi network adapter.
3rd party antivirus can cause communication issues.
Is your Windows 11 running feature release 24H2? There is an issue with this feature release affecting scanning from from multiple printer manufacturers. While not ideal, you can use Windows Fax and Scan. Microsoft has acknowledged the issue, but they have not provided a date for a patch or fix yet.
~Rick
Bay Area - CA
~R5 C (1.0.9.1) ~RF Trinity, ~RF 100 Macro, ~RF 100~400, ~RF 100~500, ~RF 200-800 +RF 1.4x TC, BG-R10, 430EX III-RT ~DxO PhotoLab Elite ~DaVinci Resolve Studio ~ImageClass MF644Cdw/MF656Cdw ~Pixel 8 ~CarePaks Are Worth It
