WeDo 2.0 Smarthub not connecting? A Bluetooth checklist

If your WeDo 2.0 Smarthub will not connect, check four things first: fresh batteries, that no other app or device is already connected to it, that Bluetooth Low Energy is on and allowed for your app, and that the hub is not paired in your system Bluetooth settings. Those four fix most cases. The full checklist below works for the old LEGO app, Scratch 3 and RoboGuru for WeDo 2.0.

Key facts

The Smarthub runs on two AA batteries or the separate Smarthub rechargeable battery (LEGO Education FAQ, Rapid Electronics).
It connects over Bluetooth Low Energy (Bluetooth 4.0) (LEGO Education FAQ).
Flashing white: waiting for a connection. Blue: connected. Flashing orange: the motor is at its power limit (LEGO hardware manual, FCC filing).
You connect by pressing the green button and choosing the hub in the app’s connect window (LEGO: how to connect to the Smarthub).

Step 1: Is the hub getting enough power?

Start here even if the hub lights up. A hub with tired batteries can still blink but fail to pair, or connect and then drop out as soon as a motor starts.

Fit two fresh AA batteries. LEGO’s FAQ says ordinary alkaline or rechargeable AA batteries both work (LEGO Education FAQ).
If you use the Smarthub rechargeable battery, charge it fully first.
Check the battery contacts for corrosion, especially on a kit that has sat in a cupboard.

Step 2: What is the hub light telling you?

Press the green button. According to LEGO’s hardware manual (FCC filing):

| Light | Meaning | | --------------- | --------------------------------------------- | | Flashing white | The hub is waiting for a Bluetooth connection | | Blue | A Bluetooth connection is established | | Flashing orange | The power to the motor is at its limit |

If there is no light at all, go back to Step 1. If the hub stops flashing before you have connected, press the green button again and connect straight away.

Step 3: Is another device already holding the hub?

A Smarthub can only be connected to one app at a time. In a classroom, the hub you are looking for is often already connected to the tablet on the next table, or to a laptop that still has Scratch open.

A solid blue light means the hub is already connected somewhere.
Close the other app, or turn off Bluetooth on the other device, and the hub will go back to flashing white.
LEGO recommends labelling every hub and renaming it so pupils can tell them apart (LEGO connect guide).

Step 4: Does your device support Bluetooth Low Energy?

The hub needs Bluetooth Low Energy, which arrived with Bluetooth 4.0. Almost every tablet and laptop sold in the last ten years has it, but older desktop PCs and some cheap USB dongles do not.

Also check app permissions:

iPhone and iPad: Settings, then the app, then make sure Bluetooth is allowed.
Android: allow the “Nearby devices” permission (Android 12 and later) or Location (older versions), and keep Bluetooth on.
Windows: make sure Bluetooth is on in Settings and that the adapter is not switched off in airplane mode.
macOS: System Settings, then Privacy and Security, then Bluetooth, and allow the app.
Linux: the Bluetooth service (BlueZ) has to be running. See our Linux guide.

Step 5: Did you pair the hub in system settings?

Most WeDo 2.0 software connects to the hub from inside the app. Pairing it in the operating system’s Bluetooth menu can stop the app from seeing it. LEGO’s own guide only asked for system pairing on Windows 8.1 (LEGO connect guide).

If the hub appears in your system Bluetooth list, choose Forget this device (iOS, macOS) or Remove device (Windows, Android), then connect again from the app.

Step 6: Are you close enough?

Bluetooth Low Energy has a short practical range indoors. While connecting, keep the hub within a metre or two of the device. Metal tables, laptop trolleys and a room full of other hubs all make it harder. In a classroom, connect one table at a time rather than all at once.

Step 7: Restart in the right order

Take the batteries out of the hub for ten seconds and put them back.
Turn Bluetooth off and on again on the device.
Close the app completely and reopen it.
Press the green button and connect.

Platform notes

Windows

LEGO documented pairing problems after the Windows 10 Fall Creators Update, and Windows 7 needed a separate BLED112 Bluetooth dongle (LEGO connect guide, LEGO: WeDo 2.0 on Windows 7). If your PC’s built-in Bluetooth is unreliable, update the adapter driver first.

Scratch 3

If you use Scratch, Scratch Link must be installed and running before you click the WeDo 2.0 extension’s connect button (Scratch help). More in our Scratch 3 guide.

RoboGuru for WeDo 2.0

The same checks apply. RoboGuru runs on iPhone and iPad, Android, a Web editor, Windows, macOS and Linux, and connects to the Smarthub from set 45300. Get it from the download page.

Frequently asked questions

Why won’t my WeDo 2.0 Smarthub connect?

The usual causes are weak batteries, another device or app already holding the hub, Bluetooth being off or lacking Bluetooth Low Energy support, or an old system-level pairing getting in the way.

What do the lights on the WeDo 2.0 Smarthub mean?

According to LEGO’s hardware manual, flashing white means the hub is waiting for a Bluetooth connection, blue means a connection is established, and flashing orange means the motor is drawing power at its limit.

Should I pair the Smarthub in my system Bluetooth settings?

Usually not. Apps such as Scratch and the official WeDo 2.0 app connect to the hub from inside the app. LEGO’s guide only asked for system pairing on Windows 8.1. If you paired the hub before, remove it from the system list and connect from the app.