DIAGNOSIS This printer uses Wi-Fi Direct and WPS for cable-free setup, but those methods can be finicky with modern routers, especially if you have a combined 2.4GHz/5GHz network name.
FIX The most reliable method is to temporarily use a USB cable for the initial network setup. 1) Plug the USB cable into the printer and your computer. 2) On the computer, open the HP Smart app (download it if you need to). It will walk you through setup and ask for your Wi-Fi network name and password. 3) Once the printer is connected to Wi-Fi and shows as 'Online' in the app, you can unplug the USB cable. The connection is now stored in the printer.
IF THAT DIDN'T WORK If you absolutely can't use a cable, try the WPS push-button method. Press and hold the Wi-Fi button on the printer's control panel for 3 seconds until the light blinks. Within 2 minutes, press the WPS button on your router. Wait for the printer's Wi-Fi light to become solid.
HEADS UP This printer only connects to 2.4 GHz Wi-Fi networks. If your router broadcasts a single name for both bands, you may need to log into your router's settings and temporarily disable the 5 GHz band just for this setup process.