There are 3 possible reasons why your bitrate may be unstable and 3 different solutions for this issue. Streamster indicators will help you to understand what causes the problem in your case.

Case 1. Processor/Encoder overloaded. CPU load indicator (1) and/or Encoder indicator (2) are red.

Solution 1. Close unnecessary applications or decrease video quality.  Use your Windows task manager to understand what applications have high CPU capacity and close them if it is possible. Reduce video resolution of FPS using Streamster main settings or encoder video quality using additional settings.

Case 2. Network problems (bad internet connection). The First 3 indicators are green, but Bitrate indicator is yellow or red.

Solution 2. Use cable internet connection instead of wireless or contact your internet provider. 

Case 3. Website problems. All 4 Streamster indicators are green, but website bitrate is lower than expected.

Solution 3. Check platform stream requirements and change your settings according to them. If your settings meet platform requirements, you can try to change stream key, try again later (it might be temporary problems on the platform) or contact support.