Guess you can apply for warranty from the retailer as maybe your TL-WPA4220 is broken. There is nothing wrong when I am running bitcoin software with TL-WPA4220.

Yes, the throughput test result is completely normal. So don't worry about it.

Strange thing, I am using bitcoin version 0.9.0 windows 32, and I haven't found anything wrong. I have used bitcoin version 0.8.5 windows 32 before, also there is no problem. Maybe you can just reset...

You have misunderstood ethernet speed with powerline speed. The speed from speedtest is ethernet speed, and the speed you have seen from utility is powerline speed. 100Mbps powerline speed is like...

Maybe you can give a try to change the channel of your WPA4220's wireless network. Because there may be wireless noise which affects your WPA4220's wireless performance.

Apparently your devices are broken. You can contact the local service center to apply for warranty.