How does DFS (Dynamic Frequency Selection) technology work in routers, and why might the Wi-Fi network disappear?

DFS, or Dynamic Frequency Selection, is a mechanism for automatically selecting radio frequency channels in the 5 GHz band. Initially, this band was actively used not only by home routers, but also by professional radar stations, meteorological radars, and military equipment. To prevent wireless networks from interfering with the operation of critical government services, international regulators required network equipment manufacturers to implement DFS algorithms.

The essence of how DFS works is that before switching a Wi-Fi network to one of the protected 5 GHz channels, the router is required to monitor the radio spectrum for a specific period of time. If the device detects radar signals during this check, the use of that channel is immediately blocked, and the router is forced to search for another available frequency. It is precisely because of this process that users may occasionally observe the sudden disappearance of the Wi-Fi network or a long reboot of the wireless module.

The main advantage of using DFS channels is access to an additional frequency band where interference from neighboring routers is typically minimal. In densely populated apartment buildings, standard non-overlapping channels are often overloaded, so switching to DFS frequencies helps significantly increase connection stability and actual wireless data transfer speeds.

If your router regularly loses connection in the 5 GHz band or takes a long time to restore operation after a reboot, it is likely constantly encountering false positives from the radar detection system. In this case, you can manually set a static channel from the lower part of the frequency range in your wireless network settings, which do not require going through the mandatory DFS procedure, thereby avoiding accidental connection drops.