This is usually a network handshake issue. Let's walk through a reset and reconnect.
First, restore the printer's network settings to default. Press and hold the Information button (the 'i') for 3 seconds until all the buttons light up. Then, press and hold the Wireless button and the Cancel button together. The printer will restart and go into wireless setup mode—you'll see the Wireless button blinking blue.
Now, reconnect using the HP Smart app. Go to 123.hp.com on your computer or phone to download it if you don't have it. Open the app, tap the plus icon or 'Add Printer', and follow the prompts. The app will guide you through connecting the printer to your Wi-Fi network. When it asks, create an HP account and register the printer.
If that didn't work: Your router might be too far away or there's interference. Move the printer and router closer together. If your router has a WPS button, you can try that method instead. On the printer control panel, press and hold the Wireless button for at least 3 seconds until the light blinks, then press the WPS button on your router within two minutes.
Heads up: Make sure you're not trying to connect while a VPN is active on your computer or phone, as that can block communication with the printer.