What is it you are trying to use Smart IPTV to view, it needs to be set up to work , usually by purchasing access to a M3U playlist and entering the MAC address of the device ( in your case your LG TV) at the setup screen, just installing it from the App Store doesn't give you access to anything... because it can be used for watching content without payment to the content right holders, if after entering a path to a M3U file, it works but intermittently or poorly , then you have no real come back with your ISP or the content provider.
I'm not suggesting that's what you are doing, but it's what can be done with this App, and although LG obviously include it on their App Store, it's not an LG App, so LG don't support it, and your ISP isn't going to worry about Apps that don't work, that's down to the App publisher , in fact , if the ISP consider its used to access content that wouldn't normally be available in that area, or being used to circumvent DRM, they may proactively try to stop access to that content.
If the path to the M3U is OK , generally they recon you need at least 20Mb download , presumably your connection exceeds this, so do you get nothing at all ( so presumably not set up correctly or invalid M3U ) or if it works but poorly after entering a M3U path, ( buffering, sound and picture out of sync etc) then there isn't much you can do about that.
