Networking over mains cables

Do the 'HomePlug' network-over-mains devices work ok?

I'm fed up with using a wireless router (at my mum's house - an old stone
built house). I'm beginning to think I need to run cat5e or cat6 cable
hither and yon but that will involve a lot of drilling and a lot of crawling
around on my tum tum under the floor.

Maybe I should use mains cable-based networking instead. Do these things
really work? Is any one particular manufacturer's product better than
anyone else's? Are the units configured in any way, eg to prevent a
neighbour (if they also have similar units) from seeing my network traffic?

--
Jeremy C B Nicoll - my opinions are my own.
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