Quick Answer: An HDMI over LAN adapter carries HDMI across Cat 5e or Cat 6 cable, and the two product families sold under that name are not interchangeable. A point to point extender passes uncompressed 1080p60 about 40 metres (130 ft) on one cable, adds under 1 ms of delay and needs no IP address. An IP encoder compresses to H.264, rides an existing switch and reaches 100 metres (330 ft) per segment, but adds 60-200 ms and can refuse protected content. Buy the extender for one screen, the encoder for a building.
Run length decides the purchase, not the connector shell. Copper twisted pair carries HDMI to roughly 40 metres (130 ft) with active electronics, and to 100 metres (330 ft) only when the video is compressed or moved onto fibre. A passive puck that merely rewires HDMI pins onto an RJ45 plug has no power input and no reclocking, so it holds 1.5 metres (5 ft) at best. HDMI is a high speed differential link with an embedded clock, not a bundle of audio pairs.
What a working adapter contains
A real unit holds an HDMI receiver, a serialiser and a twisted pair driver at the sending end, with the mirror chain at the receiving end. The transmitter reads the display EDID, copies the timing, embeds audio in the same stream and reclocks the data. Where the source is DVI, an hdmi to dvi adapter carries video only, so audio needs a separate path.
Cable class and distance limits
Cat 5e satisfies 1080p60 at 40 metres (130 ft) with a good extender; Cat 6 adds margin for 4K30 and for routes sharing a conduit with mains cable. Use shielded F/UTP where a lift motor or a dimmer rack runs alongside, terminate to T568B at both ends, and keep the copper section under 90 metres (295 ft) so a normal certification pass stays possible.
| Route | Rated run | Added delay | Verdict |
|---|
| Passive pin puck | 1.5 m (5 ft) | none | do not specify |
| Cat 5e extender, 1080p60 | 40 m (130 ft) | under 1 ms | best value |
| Cat 6 extender, 4K30 | 35 m (115 ft) | under 1 ms | balanced choice |
| IP encoder on a switch | 100 m (330 ft) per hop | 60-200 ms | many screens |
| Fibre extender kit | 300 m (1000 ft) | under 1 ms | long or noisy routes |
Point to point or over IP
Point to point extender
One transmitter feeds one receiver with no switch in between. Setup is two boxes, one cable and 12 V at each end, the cost per screen is lowest, and the link behaves like a long cable, including infrared and CEC pass through on better models.
IP encoder and decoder
An encoder turns HDMI into a multicast stream that any decoder on the LAN can join. One source reaches twenty screens, but the switch must carry the multicast group, IGMP snooping has to be configured, and every screen needs a decoder with its own address.
Latency, EDID and HDCP behaviour
EDID conflicts
The transmitter needs a valid EDID before it outputs anything. With the receiver unpowered, some units drop to 720p; a model with stored EDID memory holds 1080p and prevents a black screen after a power cut.
Protected sources
HDCP 2.2 is required at both ends for 4K discs and most streaming boxes. An extender that stops at HDCP 1.4 shows a snow field or a copyright warning instead of video.
Power, mounting and legacy displays
Both ends need local power, usually 12 V at 1 A, so plan a socket at the display and one at the rack. Behind a shallow wall plate, use a right angle adapter rather than bending a moulded plug: a 90 degree adapter to mini hdmi keeps strain off a camera body or a small monitor. Where the far end is a television with only a coax input, an hdmi to antenna modulator costs less than a second extender pair.
Practical scenarios
- Situation: 32 metres (105 ft) from a rack to a lobby display at 1080p60 – fit a Cat 6 extender pair, power both ends, and leave the far connector unterminated until the screen is on site.
- Situation: twenty menu boards fed from one player in a stockroom – use an IP encoder with IGMP snooping on the switch, accept 60 ms of delay, and budget one decoder per screen.
- Situation: a machine shop where the cable shares a tray with 480 V motor feeds – specify shielded Cat 6 or a fibre kit rated to 300 metres (1000 ft), never unshielded patch lead.
- Situation: a conference room where the source refuses to show after a power cut – choose an extender with stored EDID so the transmitter does not fall back to 720p while the display boots.
FAQ
Does an HDMI over LAN adapter work through a network switch?
Only the IP encoder type does. A point to point extender needs a direct cable between the two boxes and will not negotiate with a switch, because it sends a proprietary signal rather than Ethernet frames. Plugging an extender into a switch leaves both ends dead.
Why does 4K drop to 1080p on a long run?
4K30 needs about twice the payload of 1080p60 and 4K60 about four times, so a marginal cable that passes high definition fails at the higher timing. Reduce the resolution, move to Cat 6, or shorten the run to 35 metres (115 ft).
Can the adapter carry power to the far end?
Rarely. Most kits ship a 12 V supply for each end, and the twisted pair link is not Power over Ethernet compliant, so a PoE injector will not help. Where only one mains socket exists, choose a kit that accepts PoE input and states the wattage.
