Short answer
"Not connected" or "offline" means the ADT box in your home has lost its internet connection to ADT. It usually does not mean the alarm is broken. The usual causes are an internet outage, a new router or changed Wi-Fi password, a loose Ethernet cable, or the box having been unplugged. Confirm your internet works, check that the box has power, restart the router, then reconnect the box to your network using the steps for your system below.
On this page
First, which ADT box do you have?
ADT has sold several different systems, and the fix depends on which one is in your home. Look at the box and at the app you use.
| What you have | What it looks like | App |
|---|---|---|
| ADT Command | A wall-mounted touchscreen panel, installed by an ADT technician | ADT Control (newer accounts: ADT+) |
| ADT Pulse | An older keypad or touchscreen, plus a separate small gateway box plugged into your router with a network cable | ADT Pulse |
| ADT Smart Home Hub (Self Setup / Blue by ADT) | A tabletop hub you set up yourself, with battery sensors | ADT+ (formerly Blue by ADT) |
| ADT Base | The tabletop base sold with ADT+ systems, often alongside Google Nest devices | ADT+ |
When people search for an ADT "box" that is not connected, it is usually the Pulse gateway, the Smart Home Hub, or the ADT Base: the box that sits next to the router rather than the keypad on the wall.
Steps that fix most cases
- Check your internet. Can a phone on Wi-Fi (with mobile data turned off) or a computer load websites? If not, the problem is your internet service, and the ADT box will reconnect by itself once it comes back.
- Check power. Make sure the box is plugged in, the outlet works (outlets switched by a light switch are a common trap), and its lights are on. Most ADT hubs have a backup battery, so a box that was unplugged can keep running for a while and then go offline when the battery runs out.
- Check the cable. If the box connects with an Ethernet cable, follow it to the router and push both ends in firmly. Try a different port on the router.
- Restart the router, then the ADT box. Unplug the modem and router for 30 seconds, plug them back in, and wait until the internet is working again. Then restart the ADT box (unplug it, and only take out its backup battery if the instructions for your model say so). Give it several minutes to reconnect before checking the app again.
- Check the app. Sign out of the ADT app and back in, and make sure you are looking at the right location if your account has more than one.
You changed your router or Wi-Fi password
This is the most common reason an ADT box goes offline and stays offline. A box that connects over Wi-Fi keeps trying the old network name and password.
- Easiest fix: give the new router the same Wi-Fi name and password as the old one. The ADT box (and everything else in the house) reconnects on its own.
- ADT Command: on the touchscreen, open the Tools menu, enter your master code, and look for the Wi-Fi settings. Scan for networks, choose yours, and enter the new password. Menu names vary a little between software versions.
- ADT Pulse gateway: the gateway connects to the router with a network cable, so a password change does not affect it. A new router does mean moving the cable to the new router. If it still will not connect, call ADT; the gateway may need to be re-registered.
- Smart Home Hub and ADT Base: open the ADT+ app, go to the hub or base in your devices or settings, and look for the option to change the Wi-Fi network. If the app has no option to reconnect, plug the box into the router with an Ethernet cable if it has a port, or contact ADT support.
Use a cable if you can
A box plugged directly into the router with an Ethernet cable is the most reliable setup. It is not affected by weak Wi-Fi or by password changes. If your router is in a different room, a powerline adapter or a mesh Wi-Fi node with an Ethernet port can bring a wired connection closer to the box.
Router settings that cause repeated drop-outs
If the box keeps going offline and coming back:
- Reserve an IP address for the ADT box in your router's settings (often called DHCP reservation), so it gets the same address after every router restart.
- If your router combines 2.4 GHz and 5 GHz under one network name, many security devices only use 2.4 GHz. Some routers let you create a separate 2.4 GHz network.
- Router "security" or parental-control features can block unfamiliar devices. Check that the ADT box is not blocked or paused.
- Move the box away from the router's blind spots: inside metal cabinets, behind a TV, or in a basement corner.
Is the alarm still working while it shows not connected?
Usually, yes. The box still sounds its siren if a sensor is triggered, and the keypad or touchscreen still arms and disarms. What you lose is the app: remote arming, notifications, and live video.
Whether ADT's monitoring center still hears about an alarm depends on cellular backup. Professionally monitored ADT systems normally have a cellular connection, either built in or through a plug-in module such as the ADT CellBridge, so alarm signals can still get through when the internet is down. Self-monitored systems usually do not. If you are not sure, ask ADT whether your account has cellular backup and when it last checked in.
Sensors offline but the box is online
That is a different problem: the box is reaching ADT, but an individual sensor is not reaching the box. Replace the sensor's battery, check that it has not fallen off its mount, and move it closer or add an ADT range extender. See wireless sensor low battery.
When to call ADT
Call ADT support if the box has power, your internet works, and it still will not connect after a restart. Do not factory reset the hub or panel unless ADT tells you to: a reset can remove its link to your account and its paired sensors, and you would have to add them all again. If your ADT system came with a house you moved into, the box may still be registered to the previous owner's account; see moving into a house with an alarm system.