The network channel built into some HDMI cables
An HDMI cable can carry more than picture and sound. Some versions also include an HDMI Ethernet Channel, a small network link intended to let compatible devices pass internet data through the same cable. The cable contains conductors for that channel alongside the wires that carry audio and video.
The idea was to simplify a home theater connection. If a television and a connected player both supported the feature, one device with an internet connection could potentially share it with the other over HDMI—avoiding a separate network cable between them.
Why those wires often do nothing
The feature only works when the equipment at both ends is designed to use it. A cable cannot add networking to a television or player that lacks the required circuitry and software. Many manufacturers instead gave devices their own Wi-Fi or Ethernet ports, so the HDMI network channel had little reason to become a routine part of setup.
That leaves a mismatch: a cable may physically contain the extra conductors, but ordinary HDMI use does not need them. They sit idle while the cable carries the signals its connected devices actually exchange.
The practical takeaway is that a network-capable HDMI cable is not a substitute for checking a device’s networking features. The extra wires matter only in the uncommon setup where both connected devices support sharing data over HDMI.
