Why do RVers need WiFiRangers or any mobile router or WiFi amplifier in the first place?

A campground WiFi system typically operates several WiFi Access Points (AP) throughout a park. Depending on the design of the WiFi system there can be a considerable distance from your RV site to the nearest AP. Successfully connecting to the WiFi network involves both receiving a signal from the AP as well as returning a signal from your network back to it. Laptops, tablets, etc, typically have very low power (a few milliwatts-mW) WiFi transmitters in order to maximize battery life and their built-in antennas are small and not particularly effective. In comparison, a WiFiRanger Denali has a 1,000 mW transmitter with an advanced antenna that, itself, provides a substantial improvement in both receiving and transmitting WiFi signals. WiFiRanger indoor routers, although somewhat lower power, still provide far greater connection range than will the built-in receiver/transmitter in most consumer devices.