Advanced Device Type Management
You can force Prerender to render pages with a specific device type, which will override the automatic device detection system.
To do this, add the X-Prerender-Device-Type header with either the Mobile or Desktop value when sending the request to https://service.prerender.io.
This will only work if your account has the Mobile Optimized Rendering setting enabled in your Dashboard.

Engineer's note
The detection is not case-sensitive.