Hi, I'm a Microsoft user like you and I will try to help you as best as I can today.
The problem with the internet connection may be caused by a fault unique to the Microsoft Defender VPN setup on your iPhone. You might attempt the following troubleshooting techniques to fix this problem:
Restart the iPhone: Restarting your iPhone can occasionally fix momentary connectivity problems. After turning off your iPhone, give it a brief period of time, and then switch it back on.
Reset VPN Settings: Go to the Microsoft Defender VPN settings in the settings on your iPhone. Try wiping off the current VPN configuration and creating a new one to reset these settings.
Update Defender App: Make sure that you have the latest version of the Microsoft Defender app installed on your iPhone. Updates may contain bug fixes and improvements that could address the issue you're experiencing.
Check VPN Configuration: Review the VPN configuration settings in the Microsoft Defender app on your iPhone. Ensure that all settings are configured correctly, including server selection, protocol, and authentication credentials.
Also, you might want to temporarily disabling any other security or VPN-related apps that you may be running on your iPhone, such as firewall or third-party VPN clients, to see whether they could be interfering with Microsoft Defender VPN.
Try these steps and hopefully, it resolves your issue. If it doesn’t, you might want to contact Microsoft support for further assistance. Let me know if you have any other questions.
Best regards
Deeksha