You can give ATVIPTV a try since they offer a three-day free trial. I'm currently using this IPTV service on my Firestick and haven't experienced any buffering or delays. It offers a wide range of content from over 26 countries, including various types of updates such as sports events, football, boxing, entertainment, movies, and more. They provide a free trial for testing, so I hope this information is helpful to you.