Don't give up on the scanner yet. See this for instance, it looks like you can use this third-party tool to scan with your scanner:
https://www.hamrick.com/vuescan/canon_5600f.html?keyword=canon%20%2B5600f&gclid=CjwKCAjwnZaVBhA6EiwAVVyv9GuFph-1z4lX7g3hFsSleAGbihBBy1nGX4j188lmNW-Ac4Z2rQ2hSxoCbZUQAvD_BwE
Canon itself has stopped supporting this scanner for recent MacOS:
"Unfortunately your device is no longer supported under the selected operating system. Please feel free to view our current range of available products .
This product is compatible with the following operating systems -
- macOS 10.13 (High Sierra)
- macOS 10.12 (Sierra)
- OS X 10.10 (Yosemite)
- OS X 10.9 (Mavericks)
- OS X 10.8 (Mountain Lion)
- Mac OS X 10.7 (Lion)
- Mac OS X 10.6 (Snow Leopard)"
You might try installing the latest driver:
https://en.canon-cna.com/support/consumer_products/products/scanners/canoscan_series/canoscan_5600f.html?type=drivers&language=en&os=macos%2010.13%20(high%20sierra)
That one is for High Sierra but it might work.
I have a Canon Pixma 8120 that we have used since 2011 and even under Monterey I was able to install the drivers from Canon despite them being listed as for Sierra (10.12) or lower only. Living on borrowed time probably but it is still working!
You might also try Canon's scanner software app and see if it can connect to the scanner.
Also -- try opening Apple's native Image Capture -- can you scan using that program.
If you end up opting for a new scanner, you can simply look on the manufacturer's web site for the scanning drivers. If they offer them for Monterey, it is supported. A newer model is always best, eventually they phase out support for older devices.
