When I am at home I'd sometimes really like to use the 25 Mbit/s of my VDSL line to its full extent. That's easier said than done as my VDSL router is in the hallway while my PC is in another room. Laying a cable is not an option so I am relying on Wi-Fi. As my notebook does not reliably work with the VDSL router's built in 802.11n Wi-Fi since I upgraded the router's software I use the 802.1g Wi-Fi built into my somewhat old WRT54-GS Wi-Fi router I use a VPN gateway. That limits my transmission speeds to about 18-20 Mbit/s in practice. In other words I am falling around 5-7 Mbit/s short of what's possible with my VDSL line. Not ideal.
So I decided to do something about it and bought two 500 Mbit/s Powerline adapters. I had high hopes for the solution as the linear distance between the VDSL router and the PC is 10 meters at most. Also, most reviews on a number of web sites were very positive. Unfortunately, it seems that the the power socket in the hallway and the power socket close to my desk might be on different phases or there's something else in the way as my throughput was a meager 2 Mbit/s. Not quite the hundreds of Mbit/s I was hoping for...
I then connected the power line adapter in the bedroom and the kitchen and again I only got 2 Mbit/s each time. In the bathroom I got 7 Mbit/s. Only when I connected the the two Powerline adapters to sockets in the same room did I get the full 25 Mbit/s bandwidth of my VDSL line. The diagnosis program shipped on a CD with the adapters indicated that the line speed was 300 Mbit/s but I didn't give it a try as having the adapters in the same room is a nice exercise but worthless in practice.
I live in an apartment building in Cologne that was built in the 1980's so I don't think my power cabling is out of the ordinary. Quite a disappointing result. Looks like I have to think again about a better Wi-Fi option, Powerline's definitely not the answer for me despite seeming to be a good solution for many others.