Search is borked otherwise I would have, sorry.
Which are the best ones.
Can I run several to different rooms?
Will it be more stable than wifi?

We use them and run them to multiple rooms which are too far/have intervening walls which are too thick for wifi.  Generally very stable and when they do lose a connection I’ve never bothered figuring out if it is the powerline adapter itself or the equipment attached to it.  We use Netgear ones which seem fine.

Do you need a pair for each connection? How does it work?

Or get either Google WiFi or BT Wholehome and set up a proper mesh system. A Mate has gone down the BT route and says it’s very good indeed.

TP-Link ones work well. You need one ‘master’ and the rest are slaves, I seem to remember. You can buy packs with varying numbers of slaves included.

I think the signal can degrade if you start adding a large number.

The other option is network extenders that also work well in my experience.

Use and recommend Devolo.

You have one connected via ethernet cable to your router which acts as the “master” and then another one in each location your want to provide ethernet/WIFI to (depends on the model of adapter).

I use them all over the house/garage. Friends have them providing internet to their home office thing in the garden.

Work really well and Devolo support is great. Able to run streaming service over them and WIFI into the garage.

I have a few – a mix of Solwise and TP-Link (mixing brands is no issue). The TP-Link had slightly clearer instructions would recommend them over the Solwise. I hang a couple of wifi points off them to give decent wifi coverage of the whole house.

Few notes;
– They don’t work as well if your power is split over different rings.
– You don’t want to hang them off powerstrips. Give them their own socket. Piggyback ones are the way to go if you don’t want to lose the socket.
– Like all network stuff the Mpbs quoted is the theoretical maximum and you’ll get nowhere near it. It will still be better than wifi.
– A powerline adaptor + Ethernet switch is a great way of giving wired connections to a load off kit sitting together (eg. TV + AV stuff or home office)

You need one ‘master’ and the rest are slaves, I seem to remember. You can buy packs with varying numbers of slaves included.

I think you are remembering wrong.

EDIT; I bought a couple extra recently and on Amazon a set of one normal + one piggyback is cheaper than two normal for some reason;

One standard + one piggyback £24: https://www.amazon.co.uk/gp/product/B016ZZAVYI/ref=oh_aui_detailpage_o02_s00?ie=UTF8&th=1

Two standard £28.45:
https://www.amazon.co.uk/TP-Link-TL-PA4010KIT-Adapter-Configuration-Required/dp/B01BECPIMC/ref=sr_1_4?s=computers&ie=UTF8&qid=1518180118&sr=1-4&keywords=powerline

I use tplink ones. They work well. No real issue with them being on different circuits of extension leads. You just need one per device and one to plug into the router. Occasionally have to turn one off and on, maybe once in 6 months.

I’ve used tplink ones for SkyQ when we couldn’t get the WiFi mesh to work reliably. Had them about 18 months, and have been faultless.

I can recommend the BT Essentials 300 Wi-Fi Extenders. Our house is 3 storeys with lots of solid walls, tight corners etc and we always had lots of dead spots. We put one upstairs and one downstairs (they’re quite cheap) and now we have good signal all over.

Another recommendation for Devolo here. I use one in the garage to provide wifi to the garden and summer house and one in the dining room to provide wifi to an area that previously had none. Garage is connected to mains through the same consumer unit as the rest of the house.

guest wifi account is handy when you have folk round and the app is dead easy to use.

We now get 40mbs + in the garden (at the router we get 60) so they seem to work pretty well.

What isp are you on? Might be the freebie modem/router isnt that good.

Im with plusnet (fibre) and ditched the One hub for a new Billion modem/router and the wifi is much better in our 3 storey house now, enough so ive ditched the tplink powerline wifi extender. Only keeping tbe powerline for the Humax pvr which doesnt have wifi

Another devolo recommendation here, tho’ have no experience of other brands. Couldn’t be simpler to set up and faultless in operation.