so I got a gorgeous wireless AirPrint-capable MFD (Canon i-Sensys MF645Cx), which is connected to my Mikrotik hAP AC lite router wirelessly. My Mac is connected to the same WiFi network. The router's multicast is set to "full". The problem is, every time my printer shuts down (which it does by itself after some time of inactivity), and then I switch it back on, macOS seems unable to connect to it via AirPrint. I reset the printing system, find the printer again, and it works. Until the next shutdown.
The scanning unit of the same device has no such problem: all scanning apps, be it ExactScan or ImageCapture or Preview, are capable of detecting the scanner immediately after it is online. But the printing unit... eh.
Surprisingly, I don't have problems printing off my iPhone or iPad, both detect the printer immediately when it is on.