Is your baby monitor breaking the Wi-Fi?

Some of the worst Wi-Fi in a home is caused by a device that has nothing to do with the internet.

Published · 2 min read

In this guide
  1. Why it happens
  2. How to recognise it
  3. The five-minute test
  4. What to do about it
  5. Prove it with a map

A lot of Wi-Fi that "went bad for no reason" went bad the week a baby monitor arrived. The monitor isn't broken and neither is your router: they're simply shouting in the same room.

Why it happens

The 2.4 GHz band is shared, unlicensed radio space. Wi-Fi uses it, but so do plenty of things that aren't Wi-Fi at all:

  • Analogue and older digital baby monitors, which often transmit continuously all night.
  • Wireless cameras and video senders of the cheaper, non-Wi-Fi kind.
  • Cordless phones of the older 2.4 GHz generation. Modern DECT phones use a different band and are not the problem.
  • Wireless mouse and keyboard dongles, game controllers, wireless headphones.
  • Microwave ovens, though only while running: see the microwave and the Wi-Fi.

Wi-Fi is polite by design: it listens before transmitting. A device that transmits constantly without listening doesn't take your bandwidth so much as it takes your turn to speak.

How to recognise it

  • It's always 2.4 GHz. Devices on 5 GHz are unaffected, which is a strong clue.
  • It follows a schedule. Evenings and nights, or nap time, and it clears up when the monitor is off.
  • It's local. One room is bad, the rest of the house is fine: see Wi-Fi drops in one spot only.
  • Speed isn't the symptom; stalling is. Video calls freeze and pages hang rather than loading slowly.

The five-minute test

Switch off the baby monitor at the wall — not just the parent unit, the transmitting one — and use the room for ten minutes. Then switch it back on. If the difference is obvious, you have your answer, and you didn't need any tools to get it.

What to do about it

  1. Separate them physically. A metre or two between the monitor and the router or mesh node is often enough. Neither should be right next to the crib's transmitter.
  2. Move your own traffic to 5 GHz. Phones, laptops and TVs on 5 GHz sidestep the whole fight. If your bands share a name, see one Wi-Fi name or two.
  3. Change the Wi-Fi channel. On 2.4 GHz only channels 1, 6 and 11 don't overlap. See channel width, and why wider isn't better.
  4. Prefer a monitor that doesn't fight you. DECT-based monitors use a different band entirely; Wi-Fi monitors at least play by the same listen-before-talk rules.
  5. Check what else sits near the router. Smart home gadgets are all 2.4 GHz: see smart home devices keep dropping off.

Prove it with a map

Interference looks like distance on a signal readout, which is why people buy an extender and fix nothing. Measure the same room with the monitor on and again with it off: WiFi Heatmap shows two maps you can compare, and the difference tells you whether radio noise or the walls are the real problem.