Hi @huiwenshen,
Welcome to Trend Micro Home Users Community!
The VPN feature of the mobile app is called Web Guard and allows you to filter content when you are using your preferred browser by utilizing a local Virtual Private Network, or VPN, on your iOS/iPadOS device. However, it cannot block certain applications installed on your device.
For more information, you may check this link.
About the other concern, could you tell us the following information:
- What app have an issue with the mobile security?
- When did this happen?
- iOS version:
- Trend Micro Mobile Security version:
Looking forward to your response.