Unable to scan using Canon scanner on my iMac with macOS Sonoma.

Apple's built-in AirPrint supports the Canon TS9520 and TS9520C when the devices are networked (wired/wireless) and recognized by the Print & Scan panel's Add Printer panel and associated Bonjour discovery services. When configured, Apple's Image Capture will recognize the device and allow you to scan. No Canon Software or drivers are necessary when configured for AirPrint. No USB cable should be connected once configured for AirPrint.

Also, the optional purchase (free trial) VueScan Professional scanning software supports the TS9520/TS9520C without any Canon software or drivers necessary.

I (finally) found your printer on the Canon Europe site. It does say it's compatible with Apple AirPrint, and in fact it appears it's ONLY compatible with AirPrint when running the Sonoma MacOS. This being said, I'd probably find out how to uninstall the Canon driver software (assuming you installed it?). Then I'd reset the printing system on your Mac Reset the printing system on your Mac to solve a problem - Apple Support. Then go to the next paragraph below.

Can you review the following Canon support article and let us know exactly what's not working as shown in their guide? Canon AirPrint Guide for TS9550 Printer.

(I'm kind of puzzled why you can print on it, but scanning doesn't work 🤔. I would think that if the different WiFi frequency bands were the issue, then nothing would work.)

Just to make sure we've ruled out anything obvious:

1. Check 6 Your scanner may be locked. (Personal scanners only)
2. If IJ Scan Utility Lite or the application is running, exit it. Slide the scanner lock switch to the release position.

Based on what I read on the Canon (EU) support page, it's not clear to me that the Canon software is compatible with MacOS Sonoma.

I had the same message appear when I first tried to set up a TS9521c Canon printer but an observation: Canon doesn't display a TS9550 model in the TS series - TS9520 perhaps?

I used Canon's Wi-Fi Connection Assistant (available from Canon's Support page for the printer) to set the printer up and have had no issues since - tedious but worth the effort.

Is there any chance your WiFi is dual band, and your Mac is on, say 2.5GHz band, and your printer is on the 5GHz band? Some devices treat these as different networks, even if they are combined with one WiFi password.

What app is giving you the "Cannot communicate with scanner..." messages?

Have you tried launching the Image Capture app on your Mac and see if it recognizes your scanner?

Sorry we weren't able to resolve this issue.

It does sound to me as if this is a Canon issue. Perhaps they can confirm or deny this for you.