Why won't my DJI Mavic 4 Pro connect to the controller or phone?

A DJI Mavic 4 Pro that won't connect usually needs to be re-linked: in DJI Fly, tap Control > Connect to Aircraft, then press and hold the drone's power button for more than four seconds. "No network connection" or "account not logged in" is a different problem: the controller itself needs Wi-Fi, and you need to sign in to DJI Fly.

Mavic 4 Pro connection fixes — Three different links, three different fixes. Steps are from DJI's Mavic 4 Pro user manual for the DJI RC 2 and DJI RC Pro 2.

Link the drone and controller

The Mavic 4 Pro works with the DJI RC 2 and DJI RC Pro 2, both with DJI Fly built in. A controller bought in a combo comes linked. To link one yourself, from DJI's manual:

Power on the aircraft and the controller. Keep them within 0.5 m (about 1.5 ft) of each other.
In DJI Fly camera view, tap the settings icon, then Control > Connect to Aircraft. The controller's status LED blinks blue and it beeps.
Press and hold the aircraft's power button for more than four seconds. The drone beeps and its battery LEDs blink in sequence.
The controller beeps twice and its status LED turns solid green when linked.

Linking a new controller unlinks the old one. If the drone never beeps into linking mode, restart both devices and try again. More general steps are in DJI drone not connecting to controller.

"No network connection" or "account not logged in"

The controller needs the internet for activation, firmware updates, GEO zone unlocks and maps.

In DJI Fly, slide down twice from the top of the screen to open Quick Settings.
Turn on Wi-Fi and join a network. A phone hotspot works fine in the field.
Go back to DJI Fly and sign in to your DJI account.

Don't skip signing in. DJI's manual says flight is restricted to 30 m (98.4 ft) height and 50 m (164 ft) range when the drone isn't connected to or logged into the app. See DJI account not logged in.

DJI also recommends turning off the controller's Wi-Fi and Bluetooth during flight for the cleanest video link, so switch Wi-Fi off once you're updated.

Phone won't connect (QuickTransfer)

Your phone connects straight to the drone over Wi-Fi to download files. DJI rates it at up to 80 MB/s with a Wi-Fi 6 phone, falling to 10 MB/s on 2.4 GHz.

Turn on Bluetooth, Wi-Fi and location (positioning) on the phone.
Open DJI Fly and tap the QuickTransfer card on the home screen, or go to Album and tap the QuickTransfer icon.
The first time, press and hold the aircraft's power button to confirm.
You don't enter a Wi-Fi password in the phone's settings. DJI Fly handles it.

Allow QuickTransfer in Sleep is on by default, so a powered-off drone can still transfer files. Sleep mode turns off after 12 hours of inactivity, or when you swap the battery or plug a USB-C cable into the drone. To restore it, unplug any USB-C cable, press the power button once and wait about 15 seconds. DJI says you can only connect to an aircraft that shows the Sleep icon. More fixes are in DJI QuickTransfer not working.

Still not connecting

Update the aircraft and controller in DJI Fly, or refresh firmware with DJI Assistant 2 (Consumer Drones Series) on a computer. DJI lists the common causes of a failed update: battery below 20%, a device powered off mid-update, a dropped network or switching apps during the download. If the video link drops constantly in flight, see drone keeps losing signal. Hardware faults go to repair. More on the drone is in the Mavic 4 Pro guide.