Lag that almost unsuable when using WiFi (Rosetube)

Hi,
I tried to play using WiFi watching Rosetube on RS201E for the first time, that was almost unplayable. Then I plug the Ethernet cable in then it worked fine. After that, I plugged USB WiFi adapter from an RS150B to RS201E it work perfectly. Even after I unplug USB adapter the WiFi is working fine now.

Is there anyways to fix this problem?

Thank you.

Hello,

Than are you using WIFI now without ethernet cable and WIFI dongle but it works fine?

Yes, very weird that after removing WiFi Dongle then RS201E WiFi (without RJ45 Cable) work normal