d-lan

Hello, i've got a weird problem. when i use my D-Lan Adapter (Devolo 500+) directly i have a bitrate from 0 to 200 max. when i use my WLAN Router who is also connected to the D-Lan Adapter i have an 4500-5000 Bitrate. Can somebody tell me what happens there? I really don`t wanna stream on...