HDMI over CAT
There are 2 types of HDMI extenders over network cable. Cheaper types use a proprietary protocol for transmission. This means that the transmitter and receiver always belong together and cannot be changed.
The better extenders use HDBaseT, a connectivity standard for video, audio, data and power. By using the standard you can combine different brands or certain devices use a built-in HDBaseT receiver.
UTP (not HDBaseT compatible)
Additional receiver for AC7870: