Quick answer: An ethernet wall plug is either a fixed RJ45 socket in a wall plate, a powerline adapter that sends data over mains wiring, or a plug-in Wi-Fi repeater with one or two LAN ports. The socket is the only one that gives a real, full-speed ethernet link. Powerline adapters share the mains circuit and typically deliver 100 to 400 Mbit/s in practice, while plug-in repeaters halve Wi-Fi throughput and add latency. Choose by what you can install, not by what the box claims.
The phrase is used loosely because all three end in a wall socket and all three promise a network connection where there was none. The engineering differences are large: one is a passive connector, one modulates radio frequencies onto mains wiring, and one is a small access point. Knowing which is which avoids buying the wrong thing twice.
Three products, one name
RJ45 socket in a plate
This is a keystone jack terminated on a solid cable that runs back to a switch or patch panel. It is passive, needs no power, introduces no latency, and passes whatever the cable and jack are rated for. It is the only option that behaves exactly like a cable, because it is a cable with a connector in the middle.
Powerline adapter
A pair of adapters modulates an OFDM signal onto the mains wiring between two sockets. Throughput depends on the distance, the age of the wiring, and what else is plugged in: a phone charger with a switching supply can cut the rate noticeably. Advertised figures such as 1200 Mbit/s describe the physical layer, not the Ethernet port you get.
Plug-in repeater or access point
A repeater receives Wi-Fi, retransmits it and offers a LAN port. Because it uses the same radio for both hops, throughput roughly halves, and latency doubles. A plug-in access point connected by cable avoids that penalty but then needs the cable, which brings the problem back to the first option.
Which one solves which problem
| Option | Realistic throughput | Latency | Fit |
|---|
| RJ45 wall socket | Up to 10 Gbit/s | None added | Any permanent installation |
| Powerline, same circuit | 200 to 400 Mbit/s | 2 to 10 ms | Rented flat, no drilling |
| Powerline, across phases | Often under 100 Mbit/s | 5 to 20 ms | Avoid if possible |
| Wi-Fi repeater | Half of the uplink | Added per hop | Phones and tablets only |
Installing a real socket
Box and cable entry
Use a 35 mm deep back box and bring the cable in through a knockout, not through the same hole as a mains cable. Keep at least 50 mm between data and mains wherever they run parallel. If the wall is solid, a surface box with a short length of mini trunking is quicker and cheaper than chasing.
Termination
Punch the jack to T568B, keep the untwisted length under 13 mm, and leave a service loop behind the plate. Test the outlet before fitting the plate back: it is much easier to re-punch with the jack in your hand than through a 60 mm hole in plasterboard.
When powerline is the right answer
In a rented property, or between two rooms where no conduit exists, powerline is a legitimate compromise. Buy a pair with gigabit ports rather than 100 Mbit ports, plug both into wall sockets rather than extension leads, and keep the adapters on the same circuit. If the link rate drops when a charger is plugged in nearby, move the adapter to another socket before blaming the hardware.
Where a cable can be installed, install it. A Ethernet wall plate plus a Cat6a cable to the patch panel costs less than a pair of good powerline adapters and never needs firmware. The Cat6 LAN cable overview covers which grade to pull for a 10G future.
Labelling and documentation
A wall socket is only useful if somebody knows where the other end terminates. Label each plate with the panel port number, and label the patch lead at the panel with the room name. Photograph the panel once it is patched, and keep the image with the network documentation. When a link fails three years later, that photograph saves a walk through the building with a tone generator, and it prevents the classic mistake of unplugging the wrong port during a maintenance window.
Practical scenarios
- Rented flat, router in the hall: powerline pair with gigabit ports, both on wall sockets, and accept 200 to 300 Mbit/s rather than drilling the landlord’s walls.
- Own home, two floors: pull one Cat6 to each floor during any building work; it costs a fraction of what it costs later.
- Garage office 25 m away: a direct burial or ducted cable is the reliable answer; powerline across outbuildings often fails because they are on a different circuit.
- Garden room with Wi-Fi only: a plug-in access point with a cable back to the house beats a repeater, because the radio is not shared between the two hops.
FAQ
Is a powerline adapter as good as a cable?
No. It shares the mains with every appliance on the circuit, so throughput and latency vary through the day and drop when a switching power supply is nearby. It is a practical solution where no cable can be run, not an equivalent one.
Can I use a telephone socket as an ethernet outlet?
The cable behind it is usually untwisted or has too few pairs, so it will link at 100 Mbit/s at best and cannot be certified. Some installers reuse Cat5 cable that was pulled for phones, which does work if all four pairs are connected and the jacks are replaced.
Why does my powerline link drop at night?
Other appliances switching on and off change the noise floor on the mains. Timers, boilers, fridges and LED drivers are common culprits. Move the adapter away from such appliances, avoid extension leads, and check whether both adapters are on the same circuit.
