In the past, most people used just one WLAN router in their home, which either connected to an internet modem or had one built in. But the problem is that in many cases, one router doesn't provide sufficient coverage for your entire house. Over the past few years, router companies have added an increasing number of antennas to their devices in an attempt to provide better coverage. However, a Wi-Fi signal is simply an electromagnetic wave, and the laws of physics still apply (no matter how many antennas a device has). As such, the further away the router is from its communication partner — whether that's a phone, a computer or a smart TV — the weaker the signal strength will be. And any obstacle between the two devices will further weaken the signal. That's why having only a single router to cover a large area that has plenty of obstacles (like walls, wiring and appliances) will almost certainly result in poor Wi-Fi coverage in certain parts of the structure.