OPPO’s system includes a power management feature that automatically restricts or terminates background apps to save battery. This can cause VPN apps, including Vilanet, to disconnect or fail to stay connected.
How to fix it:
Open Recent Apps, find Vilanet, and swipe down to lock it (a lock icon will appear).
Go to Settings → App Management → Vilanet → Battery Usage / Power Saver, and disable all restrictions or choose Allow background activity.
Go to Settings → App Auto-Start Management, and enable auto-start for Vilanet.
Restart the Vilanet app.
After these steps, the VPN should maintain a stable connection.
For more details, visit OPPO’s official guide: https://www.oppo.cn/thread-398922942-1