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.
I did the same thing at first. However, many times those free websites are very unstable, especially when I was in the middle of watching something exciting. It's quite frustrating and makes you question life. On top of that, the constant ads were annoying. Later on, I went searching for a reliable IPTV service. Besides spending some money each month, I no longer had to deal with that annoyance.