Buffering with Firestick
There are many factors that effect buffering, including, but not limited to, your Country, ISP, Network, device, device location, material you are trying to stream, etc., etc,
Uninstall all the Apps that you loaded in and tried that you do not use. Keep only the Apps installed that you actually use. Lean is the best way on any streaming device. Have you tried it both on Ethernet as well as WiFi? The only one that will not work with the WiFi adapter is the original Gen 1 FireTV Stick. Make sure you are using the HDMI Adapter that comes with the Stick as well as plugging power into the wall, not the TV. You can do a restart by either unplugging it from the power and plugging it back in, or just going to: Settings/Device/Restart FireTV Devices do the OS updates automatically, but you can also check manually: Settings/Device/About/Check for System Updates. You can also try an HDMI Female to Male adapter or Cord to get the FireTV Stick away from the back of the TV, which might be hampering/restricting it from getting a good WiFi signal. Also : Settings/Applications/Collect App Usage Data .... should be turned OFF. Settings/Applications/Manage Installed Applications ... this is where you click on an App to uninstall it if not using it (Some come with the Amazon OS, which you can not install) .. Also .. you should come here periodically or if you are having issues with an App and select it and Clear Cache ... Also, usually the 2.4 GHz is a stronger signal farther away from your router, (known issues with 2,4ghz so try 5g) the 5 GHz is only better if you are closer to the router. As with any streaming device, you need a good incoming ISP service, as well as the newest DOCSYS 3 or 3.1 Modem, as well as the latest type of Router, which is AC, if you can ..... As a Final attempt, you can wipe it clean and start over like you just took it out of the box by doing a Factory Reset. Once in awhile this is necessary as sometimes the device has gotten to messed up over time with all the settings changes that were messed with. Remember though, you will have to reinstall all the third party Apps that were loaded into it, as only the ones in the Amazon Cloud will reappear once you re-register the device. Before doing this, you have to Turn ON Developer Options: Settings/Device/Developer options/ ... make sure ADB debugging is turned ON , as well as Apps from Unknown Sources is ON .... Millions of folks use the FireTv Devices flawlessly. Some countries and ISP's wreak havoc though on streaming information, which is beyond individual control, although then you can attempt VPN's, as some have done with good results, where others it has slowed the download speed.