Why your apartment Wi-Fi is slow (and what you can do about it)

Summary

The most likely cause of slow Wi-Fi in your apartment is interference from your neighbors. You’ll probably see an improvement by setting your router to only operate on 5GHz channels. Read on to learn why and what other possibilities exist.

Introduction

Through this blog post, we will explore the basic operating principles behind Wi-Fi¹:, which will allow you to understand why your home’s Wi-Fi may be slow and how you can improve it. You will see a host of footnotes with extra details, but none of those are necessary for understanding the topic.

The Facts

1. The radio frequency (RF) spectrum is, by law, divided up into sections with allowed users. Some parts of it are allocated to broadcast TV, some to cellular phones, … etc …, and some to Wi-Fi. The parts allocated to Wi-Fi are on
2. Wi-Fi is a “shared medium”: only one device can ever be talking at a time on one wifi channel. This applies even when the devices are on different networks! (E.g. your neighbor’s)
3. there are ~3 channels in the 2.4GHz band and ~20 channels in the 5GHz band
4. 2.4Ghz penetrates walls / common building materials better than 5GHz
5. Combine facts 1+2+3, and you will see that in a dense place (like your apt complex) 2.4GHz is going to be incredibly congested. Some channels on 5GHz may be congested as well

Footnotes