Today it seems that Wi-Fi is present just about everywhere. This is generally a good thing, but unfortunately there are a limited number of channels for these networks to operate on. This means that if you log onto a network that operates on top of others channel-wise, or establish your own network on a crowded channel, then your connection is going to be negatively affected.
For an easy way to find out which channels are available, YouTuber “moononournation” came up with a Wi-Fi analyzer that not only runs on the inexpensive ESP8266, but is small enough to fit inside of a Tic Tac container. This makes a great enclosure, as not only is the LCD screen protected behind clear plastic, but the charging socket is revealed by opening the (former) candy door!