Mains networking - recommendations please

I'm helping someone else now! I've finished sorting out their NTE5A and house wiring, increasing their connection speed from 1000 to 1900, which is good for here. Their problem now is that the wireless signal cannot penetrate three very thick walls (about 1m of solid stone each) and running a network cable would be almost impossible. They need this so their second machine can be used.

I've read that modern adapters that use the mains to provide a network connection work acceptably nowadays, but I have never even seen one.

What are they called?
Do they simply come as a pair of plug-in units, or can one have more than two?
What actual network speed is likely?
Are they safe?
Are they reliable?
Roughly what do they cost?
Can you recommend a good make?

Thanks.

Solwise do something called 'homeplug'. Perhaps someone with more knowledge can advise if that's the sort of thing you're after.

I've got a few of these around the house:

http://www.amazon.co.uk/devolo-dLAN-Highspeed-HomePl...

Your questions:

You can use more than two (I've got three), but speed will suffer if several are passing data at the same time- the bandwidth is simply shared.

The ones I linked to are specced at 85Mbps, but it will depend on noise levels and cable length so what you'll get can't really be predicted. Mine will stream video with no problem.

Safety and reliability- I've had no problems in five years of use, plug 'em in, connect 'em up and forget about 'em

I'll second the Devolo recommendation.
I'm currently using the 200Mbit versions and get a maximum throughput of around 40 Mbit (The units report a connection speed of 175ish) between upstairs and downstairs.
Utterly reliable in my experience.
Adds around 2ms to your ping.

Just bought two more in fact. Example

Argos are also selling them on Ebay for around the £60 mark.

I used to use the 85Mbit ones which gave a throughput around 15Mbit. Still going strong after 5 years.

Faster units are on the way AV500

I use some netgears which include a 4 port hub (which is handy when connecting to TV/PS3/SkyBox/etc - saves an additional piece of hardware). It's the XE104 - not the cheapest and perhaps not the best but I've been using them for a while and they've always worked well.

In reply to a post by ian72:

I use some netgears which include a 4 port hub (which is handy when connecting to TV/PS3/SkyBox/etc - saves an additional piece of hardware). It's the XE104 - not the cheapest and perhaps not the best but I've been using them for a while and they've always worked well.

Seconded!

Thanks everyone. I've passed the information on, it looks a perfect solution for them.

Hi, Devolo homeplug adapters info, play video�

http://www.devolo.co.uk/

In reply to a post by MrSaffron:

Faster units are on the way AV500

Looks interesting.
Should finally break through the 100Mbit real throughput barrier.