I had to restart it three times, so I guess some randomness is involved. I have an MG7150 and restarting the Windows 10 service Windows Image Acquisition (WIA) AKA stisvc did the trick. Is there a (fairly) easy way to 'reset' Windows 10 scan and printing so that it discovers that the scanner is, in fact, online? If there's some Windows service or other kind of daemon I could restart, I'd consider that an improvement over rebooting, but I haven't been able to figure out which one to target.

I've also tried to disconnect from, and reconnect to, the WiFi, but that also doesn't help. I've tried to close and restart the Windows Fax and Scan application, but that doesn't solve the problem. Sometimes, it's a bit of a bother to have to reboot the computer, so I'm looking for a way to resolve the problem that doesn't involve a reboot. If I reboot my Windows 10 laptop, it works again, so I'd suspect that the problem is in Windows, and not with the printer. This happens even though the scanner is, in fact, powered on, and, according to its own little display, connected to the WiFi. If a scanner is installed, make sure that it is powered on and connected to the computer, and then try again. When I try to scan something, I get this error message from Windows Fax and Scan: Not only can I print, but I can also scan using the Windows Fax and Scan application. Windows automatically discovered the printer on the network, and it actually works. One of the nice features of Windows 10 is that I never had to install any drivers or bloatware to get it working.

I have a WiFi-connected printer and scanner (Canon MG 5700) that I use from Windows 10.

Wifi scanner windows