Military radar can make your router switch Wi-Fi channels – here’s why

Some routers briefly drop their 5 GHz Wi-Fi connection when they detect radar, then switch channels or wait before reconnecting. This is Dynamic Frequency Selection (DFS), a requirement designed to protect radar systems that have priority over shared parts of the 5 GHz band.

In the US, routers must listen before using a DFS channel, leave it within 10 seconds of detecting radar and avoid it for at least 30 minutes. In Europe, checks can take up to 10 minutes on channels overlapping weather radar frequencies. Airport weather radars are a likely source of interference: the FAA operates 45 systems protecting 46 busy airports. DFS is legal and enabled by default; users facing frequent interruptions can choose radar-free channels, though this limits their channel options.