Start streaming with vMix

Open vMix, click stream settings. Select the H264 720p 2.5 mbps preset.

Stream Configuration

Inspect the preset's settings by by clicking on the gear icon next to the quality dropdown. Ensure they match these values:

Quality Preset Options

Lastly, clicking on the advanced tab in the Stream settings window. Make sure your user agent is set to FMLE/3.0:

User agent settings