The Apple Airport series has always been a very reliable router that is secure and easy to manage. Unfortunately, Apple is no longer selling the Airport series and left this market over for other vendors. There is a lot of marketing and voodoo pushed by the manufacturers of consumer-grade routers very little of which is real.
WiFi signals have to travel through air and physical barriers. The further the distance the weaker the signal and slower the connection. When the radio signals hit obstacles like walls, furniture, appliances, etc. the quality of the WiFi connection will degrade rapidly. For example, the pro-rated Unifi WiFi access point is mounted on a rafter in our attic allowing the shortest path to any of the rooms of our 1500sqft bungalow. With only the drywall ceiling and insulation as an obstruction to travel trough. While in the attic with a clear line of sight connection my iPhone will reach the advertised speeds and max out what we get from our internet provider. However when I move downstairs at about the same distance or less with ceiling obstructing the line of sight the speed drops in half or less. Still ample to browse the Web but not even close to what the specs advertised. This example proves that the placement of a WiFi router needs to be carefully planned to provide the best possible coverage. When distance and obstructions prevent a good connection, we need to add additional WiFi access points.
The best solution is to wire the WiFi access points to one router and centrally manage the traffic. A correct setup will allow for a smooth transition from one access point to the other while roaming from room to room or even outdoors.
If running wires to additional access points is impractical we can consider a repeater or "Mesh Routers." These devices wirelessly link together like a spider web creating a seamless network. Again often the promises on the fancy website and box can’t be realized , so you end up purchasing more units than expected.
Hackers love to use someone else their internet connection to hide their tracks or break into that network. Protect yourself and others by changing the default username and password and update the firmware on your router by logging into the webpage following the manufacturer's instructions. Another concern are the networked devices like lightbulbs, cameras or even refrigerators. It's best to move these devices and guests to separated networks from each other and your main network.