Hi there! Thanks for reaching out. I understand you're able to log in to the MyQuest website fine, but the Quest app on your iPhone is giving you trouble logging in. Let’s see if we can get this sorted out together.

A couple of quick questions first to help narrow it down:
- Are you seeing any specific error message on the app when it won’t log you in?
- Have you tried closing the app completely and reopening it before logging in again?
- Is your Quest app updated to the latest version from the App Store?
- Is your iPhone's iOS version fully updated to 18.5 as you mentioned?

Meanwhile, here are some initial steps you can try on your iPhone:

1. Force Close the Quest App: Swipe up from the bottom and pause (or double-click the Home button if your iPhone has one), then swipe the Quest app off the screen to close it completely. Relaunch and try logging in.

2. Check for App Update: Open the App Store, tap your profile icon, then scroll down to see if Quest app has an update pending. If yes, update and try again.

3. Check Network Connection: Ensure you have a stable internet connection either via Wi-Fi or cellular data.

4. Restart your Phone: Sometimes a simple restart of the iPhone can clear temporary glitches.

5. Reinstall the Quest App: If none of the above works, uninstall the app, then reinstall it from the App Store. This often clears out any app-specific issues.

If you’ve already tried these or if the problem continues, please let me know the exact error message, if any, and I can guide you through more advanced troubleshooting.

How does that sound?

I have done all that.

Thanks for letting me know that you've already gone through the basic steps like closing, updating, reinstalling the app, and restarting your phone. Since the website login works fine but the app still won’t let you log in, it suggests the issue might be more specific to the app or your account within it.

Here are a few deeper steps we can try next:

1. Clear App Cache and Data (if possible): On iOS, there's no direct way to clear cache except reinstalling the app, which you did. So likely no extra benefit here, but sometimes toggling app permissions can help.

2. Check App Permissions: Go to your iPhone Settings > Scroll down to Quest app > Make sure permissions like Cellular Data and Background App Refresh are enabled. Sometimes limited permissions can block app functionality.

3. Check for any Account or Identity Verification: Sometimes MyQuest requires identity verification for the app even if the website login works. When you try to log in, does it prompt you for any verification step like entering a code or verifying identity via email or phone?

4. Try Logging in on Another Device or via Another Network: This can help isolate if the issue is your device or internet connection.

5. Check for Known Service Outages or App Issues: Occasionally, Quest app servers can have temporary problems affecting login. You could check the official Quest Diagnostics support or status page to confirm.

If none of these approaches resolve it, I recommend contacting MyQuest support directly for account-specific issues. You can reach them by email at [email protected] or via their support page.

Would you be able to share any error messages or screen details you see when the app login fails? That info can help me pinpoint the problem more precisely.