Solving playback issues

[Macguyver]

Hi all, new to the community. 

Just purchased a Streaming Stick 4K and I'm setting it up for my grandmother to use, testing out the simplicity of the experience. Generally good, I think she will be able to handle it, BUT... I am having lots of buffering problems. Here's where I am now:

Connected to 200-300Mbps Comcast on a very stable trunk line. 
Chromecast, Amazon app in TV or Chromecast, Comcast Flex box all work flawlessly.
Multiple devices can stream concurrently without any trouble.

Roku buffers like crazy on all channels/streams tested at 4K
Lowered res to 1080p, better but still buffers
Roku reports 5G wifi signal is EXCELLENT on Ch 153, bandwidth is good @ 33Mbps while at same time speedtest.net shows 235Mbps over 12Mbps and the stick is less than 20ft from Netgear C6300 router. 

At this point I must say I am not impressed! Hope there is some simple explanation/fix!

[renojim]

All I could suggest is trying a different Wi-Fi channel or even connecting to a 2.4GHz channel.  Don't fall for the "just use Auto" nonsense.  Pick a channel and stick with it until you find a good reason to change.  There's plenty of apps you can use on a phone/tablet to show you which channels are the most crowded or least used.  You can also try the free short HDMI extender cable that Roku offers, although I think the current sticks use the so-called "long-range Wi-Fi receiver" (a bump in the USB cable) which pretty much rules out the TV itself causing interference.

https://my.roku.com/hdmi

[Macguyver]

Thanks for the reply. So help me understand - is the "bump in the power cable" actually the receiver or is it just the antenna or what? 

If so, Roku informing the buyers - who are expected to install the unit successfully - that this needs to be placed away from metal/wires/sources of RF interference might be helpful... 

[makaiguy]

@Macguyver-

Earlier versions of the Streaming Stick had the WiFi receivers built into the stick.  When the stick is plugged directly into the TV's HDMI port, the extreme proximity to the set allowed low level radiation from some sets to interfere with WiFi reception.  On current Streaming Stick models, the WiFi receiver is moved outside the set and into a module in the USB cable which gets it several inches away from the HDMI port.  I've not heard of there being interference problems due to proximity to the TV with these models.