Archive for July, 2021


Some musings on Powerline adapters

July 12, 2021

I’ve been using a set of Powerline adapters in my home for several years. I’ve also recommended Powerline to several of my friends and family to solve networking problems in their homes. But they’re not a panacea for all ills. There are some idiosyncrasies which I discuss here. I hope this proves useful to someone.

Note: I’m writing from a UK perspective. While not a qualified electrician, I’m familiar with UK domestic power wiring (240V). I also have a passing acquaintance with European (Portuguese and Danish, 220V) and US (110V) domestic wiring.

What is Powerline?

Powerline (also known as Homeplug) is a technology that uses the mains power cables in your home to carry computer network signals to deliver a network – usually your broadband connection – to places in your home that are otherwise hard to reach. The signals are carried by a high-frequency radio signal over the copper electrical cables in the wall. It’s a technology designed only for domestic networks. It’s not intended for commercial use.

You plug an Ethernet cable from your router, or a point on your existing network, into one Powerline adapter which is plugged into an electric wall power socket. Then you plug a second adapter into a power socket somewhere else in your home and run an Ethernet cable from it to your remote device, which could be a computer, a wireless access point, a TV or a switch to which you connect other computing devices.

Example of the use of Powerline in a home

What types of Powerline adapters are there?

There are different versions for different power systems including US power plugs, UK power plugs, European (Schuko) power plugs and Australian power plugs.

There are versions that occupy a power socket, and there are versions which present a power socket when they’re plugged in; these are known as “pass through” adapters.

A pair of Powerline pass through adapters (UK version)

And there are different speed adapters. The lowest speed, the original versions, were labelled 200 Megabits per second (Mbps). There are 400Mbps, 500Mbps, 600Mbps, 1000Mbps, 1200Mbps and 2000Mbps versions. But in real life I’ve been unable to achieve anything near the claimed maximum speed, so I’d suggest you use a higher speed version than the network you’re trying to connect. I’m using 2000Mbps adapters to carry a 74Mbps network; my neighbour is using much less expensive 600Mbps adapters to carry a 12Mbps network.

And there are lots of manufacturers. In principle, adapters should all inter-operate, but the whole network will drop back to the speed of the slowest adapter, and each manufacturer has slightly different ways of setting up and configuring devices, so it’s generally easiest to use a set of adapters of the same speed all from the same manufacturer if you can. I’ve deployed TP-Link devices and I’m very happy with the build quality, reliability, operation, configuration and performance.

Some adapters offer more than one Ethernet port, so you can use them as a mini switch, connecting more than one device. Some adapters have a WiFi access point built in, so you can instantly set up a new WiFi network without any other devices, or you can use Powerline adapters to extend an existing WiFi network.

This pair of adapters shows one that combines both multiple Ethernet ports and a wireless access point

Decide how you want to use Powerline in your home and then select appropriate devices.

Will Powerline work on any home electric circuit?

To get the best performance you should plug the Powerline adapters directly into a wall socket – extension cables and particularly surge protection devices will attenuate the signal or even filter it out altogether.

Furthermore, it’s recommended that adapters are plugged into the same electrical circuit. Some houses have a separate circuit (ring main in the UK) upstairs from the one downstairs, and some houses which have been extended may have a separate circuit in the new build from the original building. Almost all houses have a separate circuit for sockets in the kitchen.

This doesn’t mean they won’t work across circuits, but they may not. Much seems to depend on how the circuits are protected. Older fused circuits appear to allow Powerline adapters to work across circuits; mini circuit breakers (MCBs) also seem to work, but residual current devices (RCDs) are more problematic. You may need to borrow a pair of adapters from a friend and try them, or make sure you can return the Powerline adapters to your supplier if they don’t work in your home.

Will Powerline work across phases?

In the UK, almost all domestic properties are supplied with single-phase power, but in other countries three-phase is more usual. Powerline adapters aren’t designed to work across phases, so if you’re trying to use them in a three-phase installation you may need to try and rearrange the circuits so the sockets you are trying to connect are both on the same phase. Consult an electrician.

You may be able to use an additional pair of Powerline adapters to bridge phases – I discuss this in more detail later. If you’re in the USA you may be more likely to get them to work across phases – that’s because you are very likely to have a 3-phase 110V installation and a high-power device that bridges two or even three phases. This may allow the Powerline signals to pass. There’s no hard and fast rule about whether they’ll work or not. You’ll just have to try it.

Are there any problems using Powerline?

Because the signal is carried on domestic wiring by high-frequency radio it may interfere with other devices – radio hams have reported Powerline causing interference with their radio equipment Also Powerline itself can be affected by interference from other devices plugged into the power network – I’ve seen reports that microwave ovens cause interference to the Powerline network when they’re operating.

Is my Powerline network secure?

All Powerline adapters are secured with a private key. They are configured by default with a standard key, so out of the box all adapters should work together, even those from different manufacturers.

It’s unlikely that your signal will pass your electric meter. It is also unlikely to pass onto another electrical phase, so it’s very unlikely that your neighbour will be able to connect to your network. But if you live in an apartment block, or in a shared house, then it may be advisable to change the encryption on your network to avoid possible eavesdropping.

All Powerline adapters support this. You can force one of your adapters to generate a new, random, private key and then pair the others with it. Consult your user’s manual on how to do this as each manufacturer, and even different models, may do it differently.

Can I use more than two adapters?

Yes, you can. If you’re using the default configuration you can simply plug in another adapter. If you’ve changed the encryption you will need to pair the new adapter with one of the existing adapters. Again, consult your user manual(s) on how to do that.

My experience is that adding a third and a fourth adapter worked fine, but more than that degraded performance significantly. I currently use three on my home network. They are all on the same electrical circuit, and with broadband speed at the router of 74Mbps I can achieve a 70Mbps connection at each of the remote adapters.

If I can’t get them to work well across electrical circuits, can I bridge them?

You can, but I’ve tried it in my home and my experience suggests that the performance may still be significantly reduced.

You will need to find a socket on one circuit that’s physically close to a socket on the other circuit, plug a Powerline adapter into each of these, and connect them together with an Ethernet cable.

However, to avoid creating a network loop, which will cause problems, you must arrange that the adapters on one circuit are unable to communicate with those on the other circuit via the electric cabling. To do this pair one set of adapters with a new private key (see above and refer to your user manual). You’ll end up with two adapters on one circuit using default encryption, and two adapters on the other circuit, paired together using a new random private key. Then you connect an adapter on one circuit by Ethernet cable to an adapter on the other circuit, creating a bridge.

I believe it is possible to use a specialist connector to bridge circuits at the fuse box/consumer unit, but I’ve only seen devices that do this for 110V US circuits. I’ve not found a UK 240V or a European 220V version.

Is Powerline better than wireless networking?

This depends on the situation, but in my opinion, yes. My networking mantra is, “If you can wire it, wire it”. Connecting networks with physical cables is more reliable, more secure, and usually more performant than wireless.

But if you have multiple electrical circuits and have problems getting Powerline to work effectively then short of running an Ethernet cable round your house – which can be messy and expensive – wireless may be the better solution.

I use both. I prefer Powerline, but I have a room which is on an electrical circuit which won’t work reliably with Powerline from my router no matter how it’s connected. So I’ve installed a wireless repeater to get a decent bandwidth signal to the smart TV in that room.


Why low-cost long-haul airlines will always fail

July 6, 2021

I read an article in the Guardian today about a couple who had booked a transatlantic flight with Norwegian Air. Due to Covid they were unable to go. Ultimately Norwegian cancelled the flight, but this couple unwisely accepted vouchers before this happened. Now Norwegian has withdrawn from transatlantic flghts the couple have a lot of vouchers valid only for European travel.

As the article explains, they were unwise to choose vouchers rather than wait for Norwegian to cancel the flight in which case they’d have been entitled to a full refund. But that’s not the point of my post. The point of my post is that low-cost long-haul carriers will always fail, eventually.

There are lots of previous examples. Laker’s AirTrain was the first of many. Braniff, Wow and others followed. Norwegian is just the latest.

Now Defunct WOW Airlines

You see the low-cost airline model can work for short haul. Most short-haul flights are two hours or less. And short-haul flights usually (for a full-cost carrier) take between 45 minutes and an hour to turn around for the return leg. Low-cost airlines reduce this to about 20 minutes. It can’t be any less because the aircraft brakes have to cool from the landing in order to work effectively in an emergency on take off.

But the advantage is that if your aircraft is flying, on average, 90 minute legs, and turning around in less than 30 minutes, then it can operate up to 12 legs in 24 hours. A full-service carrier flying the same route can fly only 9 legs in the same 24 hours, so the low-cost carrier can get another three plane-loads of people to pay for seats. Of course most aircraft aren’t scheduled fully for 24 hours, but the principle is clear: a low-cost carrier generally can get two extra legs a day from each aircraft it operates.

This, combined with the “no-frills” approach of minimal luggage allowances, all extras to be paid for, having the cabin crew clean the ‘plane and trying to flog lottery tickets and tickets for onward travel on board (on all of which the airline makes a margin) enables them to make the upfront advertised cost of each seat much lower than a full-service airline.

That’s how it works.

But it can’t work in long-haul. In long-haul most aircraft fly one or two legs in 24 hours. So shaving 30 minutes off each turnaround gains an hour a day – not enough to fly another long-haul leg. If airlines operate the latest generation of fuel-efficient aircraft then the no-frills savings and add-on revenues might just make a low-cost airline viable provided all flights operate close to 100% full. But this is tricky at the best of times, often requiring overbooking and then bouncing some passengers off the flight. This doesn’t endear you to your customers, so most full-service airlines aim to achieve an average of better than 80% loading. Low-cost carriers can’t afford loading this low, there just isn’t enough margin on the revenue they generate. Also full-service airlines have premium cabins (Premium Economy, Business and First Class) – this isn’t common on low-cost services, so the additional revenue from premium cabins is denied to them.

Then there’s another problem; having enough aircraft, and crews. If you’re flying short-haul around Europe and one of your ‘planes breaks, then it’s generally not a problem to find another one to rescue the passengers. It’s easier for a full-service airline as their higher revenues means they may well have a spare aircraft available and can call crews up quickly. Low-cost airlines can do it although it may take a bit longer and it may be more effective to rebook your passengers on another airline – or just abandon them, as some low-cost carriers have done in the past .

If you’re flying long-haul then it’s much harder. The larger, full-service airlines can usually find another aircraft although it may take up to 24 hours to get it where it’s needed, as I’ve experienced on a couple of occasions. But when this happened to some friends of mine who were booked to fly on Norwegian to Los Angeles for a wedding, there was no replacement aircraft. They were three days late, ended up flying on a plane chartered by Norwegian as the airline didn’t have a replacement, and they missed the wedding!

Image of a Norwegian Air Boeing Dreamliner
A Norwegian long-haul Boeing Dreamliner

Norwegian has managed to keep operating its long-haul services for longer than most of its predecessors, but that’s mainly because it had a profitable European short-haul business to subsidise the losses. but the Covid pandemic put paid to that. So it’s pulled out of transatlantic flying.

I could have told you it would. In fact I told several people right at the start when Norwegian announced it would be offering low-cost transatlantic travel that this would happen. I couldn’t predict when, but it was going to happen.

I’m reminded of Sir Richard Branson’s famous quote, “The way to make a small fortune with an airline is to start with a large fortune.” He should know. He ended up running a full-service transatlantic airline – very good it is too – but it’s not low-cost.