Hello, can you please describe the source of the stream, and the details?
What is the video codec?
What is the audio codec?
Most Android devices support RTSP/RTP streaming. When streaming to an Android device using RTSP/RTP, the RTP portion must flow over UDP. Android doesn't support RTSP/RTP interleaved (RTP over TCP). This means that if UDP is unavailable for RTP playback, RTP over TCP won't work as a failover and your stream won't play. Android devices can't play MP3 streams over RTSP/RTP in any combination (audio/video or audio-only).
You can playback in VLC, look at Tools > Codec info. Is there one set of audio and video, or two? If there are two, that indicates that UDP ports are blocked or not mapped properly. VLC is able to failover from UDP to TCP, and that is why you see two audio and two video blocks in that case. However many Android and other devices use UDP and are not able to failover.
Otherwise, it might be an encoding problem. Make sure it is h.264 Baseline 3 or lower video, and AAC audio.
Please take a look at this guide for more troubleshooting tips: