My Canon MF642 will print fine but it will not scan with the new Sequoia Version 15.0

The Canon MF642Cdw is listed as a model supporting AirPrint.

About AirPrint - Apple Support

Printing should not require additional drivers. Generally speaking, Image Capture is often used for scanning with AirPrint printer/scanners (depending on the model, an additional driver may or may not be needed).

The Canon support site has Scanner Driver & Utilities for Mac V2.15.17 [macOS 10.14.6 - macOS 15]. I do not know whether these are required, or if they would change anything in this case. See also the More Download Info link for details. Is this something that you have tested already?

https://www.csai.canon.com/support/p/color-imageclass-mf642cdw (DOWNLOADS -> Software & Drivers -> 1. Mac -> 2. macOS Sequoia -> 3.)

If necessary, if nothing else works, a paid third-party driver VueScan (https://www.hamrick.com/vuescan/canon_mf642.html) could perhaps be of interest (free trial version available).

Try this:

go to Privacy and Security>Local Network and see if you can find a Canon file and turn it on. This may not be the case, so I would turn them all on and see if you can scan. Then turn off whichever you choose to turn off. So, you can by a process of elimination figure which is the Canon culprit.

This may not be your cure, but worth a try. The files in Local Network are not always obvious as to who is generating them

Hope this helps

My notes...

Failed to open a connection to the device (-21345)

Failed to open a connection to the device (-21355)

Disabling IPv6 from the printer's control panel may resolve this issue.