The reality is that many different kinds of common household items and other types of devices can interfere with a given wireless signal or compromise a network with signal noise. That has led to some advanced research into how to make Wi-Fi systems more reliable and how to deal with the flood of signal transmission that’s happening in any given space.
Some of the most significant signal interference is coming from cellular phone infrastructure. Cordless phones and Bluetooth headsets can produce wireless interference, but so can the larger installations such as cellular phone towers.
Other kinds of signal interference are caused by regular household devices, some of which aren’t commonly thought of as Wi-Fi relayers or signal generators. Microwave ovens can produce significant interference. So can some kinds of baby monitors. Household users should consider wireless router placement in light of the fact that many of these devices can be a source of interaction or interference.
Other types of interruption are caused by new types of smart home appliances. Local governments are promoting the installation of smart meters in homes, but these can also cause some kinds of signal interference. Smart home appliances may also be sources of signal noise that can have a negative impact on a network.
Other wireless systems can also have a significant impact on a network. That has led to some debate about how to set up local systems for wireless access. For instance, efforts to secure municipal Wi-Fi service have consistently progressed, despite many types of obstruction and protest from big telecom providers.
In general, anything with a large electromagnetic field can interfere with Wi-Fi signals. That includes significant power sources, some types of LCD monitors and displays, or cable or direct satellite service infrastructure. WiFi mesh systems can be effective in addressing interference by extending connectivity and increasing broadcast strength.
Those who are interested in work on modern wireless signal integrity can research standards from the IEEE, a key standards agency for electronics.