WiFi extenders come in single-, double-, or triple-band frequencies. A single-band router operates on a 2.4 GHz band. A dual-band WiFi extender runs on either a 2.4 GHz band or a 5 GHz band. The speed of your signal is affected by how many devices are drawing from it—smartphones, security systems, computers, e-tablets, etc. If you’re receiving a slow signal, selecting a higher frequency on a device will improve your internet speed. A triple-band router has the option of providing an even faster speed at 5.7 GHz.