try OTT Navigator
however buffering might be caused by multiple issues, so it might be that you need changing buffer size or some codecs settings to match your provider and connection, if buffering issues still persists
IPTV Smarters Pro application is the Media Player application for Android TV, Android Phone, and Android Tab. Fully customizable and branded for OTT service providers.
Are you willing to try a new provider. I can make you a free trial to see if you get better results
Try Televizo.
I think you should have to use IPTV Smarters Pro v3.0.0. Because Smarters Has just release its new version v3.0.0. And many bugs and issues resolved in this Update and now App loads fast.
It's not the apps. It's your setup. Doesn't matter what app you use. Fix your setup and your buffering will go away. If not your setup, it's your provider