Why won't my DJI Mini 3 connect to the controller or phone?

A DJI Mini 3 that won't connect to its controller usually just needs to be re-paired: in DJI Fly, tap Control > Pair to Aircraft (Link), then press and hold the drone's power button for more than four seconds. "No network connection" or "no internet connection" is a different issue: your phone or DJI RC needs internet for activation and updates.

Re-pair a DJI Mini 3 — Linking steps from DJI's Mini 3 user manual. Pairing a new controller automatically unlinks the old one.

Re-pair the drone and controller

The Mini 3 works with two controllers: the DJI RC-N1 (uses your phone) and the DJI RC (built-in screen). A controller bought with the drone 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).
Open DJI Fly. With the RC-N1, connect your phone first.
In camera view, tap the settings icon and select Control, then Pair to Aircraft (Link).
Press and hold the aircraft's power button for more than four seconds. It beeps once when it's ready to link.
When linking succeeds, the drone beeps twice and the controller's battery level LEDs turn solid.

Linking a new controller unlinks the old one from that drone. For more help, see DJI drone not connecting to controller.

Phone won't connect to the RC-N1

Use the right cable: the RC-N1 comes with Lightning, Micro USB and USB-C cables. Use one that matches your phone.
DJI says to connect the end of the cable without the controller logo to your phone.
Update DJI Fly and your phone's operating system.
Close and reopen DJI Fly after connecting the cable.

Still no luck? See RC not connected to mobile device.

"No network connection" or "no internet"

The Mini 3 needs internet for activation before first flight, plus firmware updates and GEO zone unlocks.

With the RC-N1: your phone supplies the internet. Turn on mobile data or Wi-Fi.
With the DJI RC: slide down twice from the top of the screen in DJI Fly to open Quick Settings, then tap and hold the Wi-Fi icon to join a network or a phone hotspot.

Then sign in to your DJI account in DJI Fly. DJI's manual warns that flight is limited to 30 m (98.4 ft) height and 50 m (164 ft) range when you aren't connected or logged in. See DJI account not logged in. DJI recommends switching Wi-Fi and Bluetooth off on the controller during flight for the best video link.

Drone won't connect to your phone for downloads

That's QuickTransfer, which uses Wi-Fi between the drone and phone. On the Mini 3 you switch it on by pressing the drone's power button three times quickly. Full steps are in Mini 3 QuickTransfer not working.

Still not pairing

Charge both devices. Firmware updates fail below 20% battery, according to DJI.
Update the aircraft and controller firmware in DJI Fly, or with DJI Assistant 2 (Consumer Drones Series).
If the drone never beeps into linking mode, or the lights show solid red, contact DJI or start a repair.

More on this drone is in the Mini 3 guide.