Start with a simple comparison
Note whether the problem affects one authorised item or several. Test the connection near the viewing device, and compare wired access with Wi-Fi if available. A single speed reading does not describe every interruption.
Keep the result, not just the setting
Try one documented player adjustment and note whether it helps. Revert it if it does not. Report persistent problems with the time, device and app version; a brand name or a display's advertised resolution is not a playback guarantee.