I have the exact same problem. My internetspeed is 400 download and 40 upload.

The upload goes at full speed but the download never goes faster than 100Mbps.

The TPlink software tool says the connection between the two powerline adapters is more than 700Mbps but I don't even reach my full internet speed.

I also tried them next to each other like you did but with the same result; Full upload (40Mbps) and only 100Mbps download.

I tried multiple setups. I reached my full internet speed when connecting directly but every time I connect to the powerline adapter it slows down. 

I also avoided all "noisy" appliances which could cause interference on the powerline. 

Could this be a problem with the hardware of the adapters?

• I have the same problem -- ethernet capacity capped at 100mbps.
• It looks like the ethernet ports are only negotiating 10/100 mbps speeds.
   
• For example, advertised modes by the AV2000 ethernet ports only preset the following:

  • 10baseT/Half

  • 10baseT/Full

  • 100baseT/Half

  • 100baseT/Full

So, obviously my 1000mbps capable device is only negotiating 100baseT/Full and the overall data transfer remains capped at 100mbps only.

@TP-Link please offer a solution or we'll have to return the device. Thank you.