Hi there! I understand you're having trouble with the Netvue app on your iPhone iOS 18.7—it won’t open and can’t connect to the internet, while other apps are working fine. Let's work through this together.

First, I want to clarify a couple of things to better assist:
1. Is your iPhone connected to Wi-Fi or cellular data when trying the app?
2. When you say the app won't open, does it crash immediately or just stay on a loading screen?
3. Have you tried restarting your iPhone or reinstalling the app already?

Meanwhile, here are some common troubleshooting steps for app connectivity issues with Netvue:

1. Check Wi-Fi Band: Netvue devices and their app typically require a 2.4 GHz Wi-Fi network. Even if other stuff works, make sure your iPhone is connected to the 2.4 GHz band, not 5 GHz, as the app may not work properly otherwise.

2. Restart Your iPhone: A simple restart can clear out temporary glitches.

3. Update the App: Make sure the Netvue app you installed is the latest version from the App Store. Sometimes app crashes happen due to outdated versions incompatible with your iOS.

4. Clear App Cache: On iOS, this usually means uninstalling and reinstalling the app to ensure no corrupt data is causing the issue.

5. Reset Network Settings on iPhone: Go to Settings > General > Reset > Reset Network Settings. This can fix network conflicts affecting the app's connectivity.

6. Check App Permissions: Ensure the app has permissions to use your local network and required features. Go to Settings > Netvue app and enable necessary toggles.

If after this the app still won't open or connect, there may be a more specific issue. Sometimes other users reported intermittent app connection problems, and the key was confirming the Wi-Fi band or even updating router firmware1 2.

Would you like me to guide you through resetting network settings or checking your Wi-Fi band on your iPhone? Also, if you tried any of these steps, please let me know so I can suggest the next best option.