I am a long time user of the Devolo 200MB AV+. It works ok but not well enough if you use internet all day long for work.
I switched to the 500 hoping for improved performance. Well, it's a disappointment. The data transfer rate as well as the quality of the signal are exactly the same as the 200.
Conclusion: unless you can test beforehand save your money and buy the 200AV serie.
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