If you have walls open (such as in an unfinished house), implement Cat-6 cables and wire your home with ethernet before it gets logistically difficult to do so. Wired is always faster than Wireless from the same source.
If you are looking to lengthen the range of your WiFi using an external antenna that can aim in a particular spot, check out RadioLabs.com (Leo's favorite source for WiFi antenna solutions). This can solve issues that Mesh Wifi would not, so for large home areas try a product from RadioLabs. Make sure to include the "S" at the end or else you'll end up at a different podcast website!
Sometimes, you and your neighbors will have intersecting and overlapping WiFi networks in the surrounding area. Normally, these impacting factors are quite hidden from sight, but the tool "inSSIDer" allows you to see the details. With the software, you can assess channel, channel width, signal strength, WiFi generation, maximum data rate, and security. You can download a Windows version or a Mac OS version for your computer, and use what you learn to improve your speed!
Ken has an Eero mesh router, but he's concerned because he has several "internet of things" devices and he hears that mesh routers don't like them. Leo says that is the current problem, and it may be that the devices aren't smart enough to handle the mesh way of handling the network. They're working on it and Leo says that a fix will some sooner or later. But in the meantime, hardwiring to the router may be the best solution.