So I bought the pack "Devolo dLAN 500 Duo +" and I do not regret it at all. The small leaflet is very well detailed contrary to what I read in other reviews (missing user guide?), The installation was made in 3min (and I have to go up one floor: p)
It plugs into the power strip on top and then connect the modem / router. Then we did the same PC side. It syncs together via small buttons under the CPL box starting with the modem side box ... That's it! Internet works great!
Just take good care to respect the manufacturer's installation recommendations for the maximum throughput.
I highly recommend this product to any user seeking a reliable remote internet solution.
Although not necessarily cheap, quality pack is there and it costs less that some wifi cards.