I've had the same experience on the alphas and all 3 betas: wifi drops after about 1-3 minutes of streaming video. Works fine on LibreELEC Jarvis.
This is the hardware: ION 3D Series - ASRock Inc.
- Intel® Atom™ D525 Dual Core Processor
- Mobile Intel® ICH8M chipset
- 2GB DDR2 800MHz
- NVIDIA® GT218-ION Graphics, NVIDIA® 3DTV Play Capable
- 7.1 CH HD Audio with DTS
- Supports ASRock XFast USB, XFast LAN Technologies
Logs attached below: