HP Officejet Pro8620 is not connecting to WiFi to fix this issue; you can follow the steps given below.
Step 1: Press and move your finger across the screen on the printer control panel, then touch Setup, then Network Setup.
Step 2: Touch Yes after selecting Restore Network Defaults.
Step 3: The network defaults have been restored, according to a message.
Step 4: Select OK.
Step 1: Turn off the computer, router, and printer.
Step 2: Allow 60 seconds to pass.
Step 3: Wait for all of the lights to stabilize before turning on the Router.
Step 4: Allow the printer to configure itself after turning it on.
Step 5: Switch on your PC.
Step 1: Touch and slide your finger across the screen on the printer control panel display, then touch Setup.
Step 2: Setup your network with a touch.
Step 3: Touch the Wireless Settings.
Step 4: Touch the Wireless Setup Wizard to get started.