IPTV Streaming app bug fixes **URGENT**

I'm now looking for a "permanent" android developer who has previous experience working with IPTV Streaming apps for Android TVBoxes. ****Please provide related experience in your bid, and the shortest timeframe possible as this is a VERY URGENT project and VERY TIME SENSITIVE**** I already have a working app, and have the complete source code for it, but need to fix some bugs and eventually add new features to the app. 1st bug: on many Android 4.x devices, my app is showing an error msg on startup "Request is expired", and will not work unless I clear the app data, then next time it starts up, it has the same issue again. 2nd bug: on all Android 4.2.2 devices, my app plays the audio/video not synchronized, and sometimes it plays fine, but most of the time it's really bad. however it works perfectly fine even on older device with 4.0.3 and newer devices 4.4.2, 5.1.1, 6.0.1. 3rd bug: i just received a new android tvbox with Android 7.x in it, and as soon as i change the channel, the audio plays but the picture is frozen for 5-30 seconds, then audio/video play perfectly fine. this happens on all channels, i'm only guessing that it might be related to the media player in the app, but i'm not sure. All work needs to be done through teamviewer as i will not share the source code with anyone. once all 3 major bugs are resolved, then i will provide you the source code so you can continue the remainder of the little bugs and adding new features to the app, as the list of bugs and fixes that we need is more than 10 items. so please quote me for the above 3 bugs only, and for the timeframe as that's VERY important for me. milestone for the full agreed amount will be deposited, but no payment will be released until the FULL project is completed successfully. no partial payments unless agreed before being awarded.