I too have the same problem.My ISP is AT&T and when I run speed test I'm getting around 35Mbps on all my WiFi devices so I know that my modem is transmitting at the correct speed. I rebooted the modem, rebooted the set-top box, I logged off and back on. I unplugged and re-plugged the devices. I checked the IP addresses so there is no overlap. I made sure no other devices were on that would suck the bandwidth. I reinstalled the Netflix App in Smart Hub, I made sure the TV software was at the latest release and I'm still getting 0.27mbps speed when streaming Netflix. Through all this process of elimination I believe that the WiFi receiver on the TV may have gone bad.
I would like to know if there is some diagnostic that can run on...