Hello! I understand you're having trouble logging into Lineage2M on your iPhone using mobile data. Let's see if we can get you back into the game.

First, could you tell me:
- Are you able to connect to the internet on your phone using mobile data when browsing or using other apps?
- Does the issue happen only with Lineage2M or with other online games/apps as well?
- Have you tried switching off Wi-Fi completely to ensure the phone is only using cellular data when launching Lineage2M?

Meanwhile, here are some steps you can try that often resolve connection issues using mobile data on iOS 18.5:

1. Check Cellular Data Settings for Lineage2M:
- Go to Settings > Cellular.
- Scroll down to find Lineage2M.
- Make sure the toggle next to it is ON to allow cellular data use.

2. Toggle Airplane Mode:
- Swipe down from the top-right corner to open Control Center.
- Turn Airplane Mode ON for about 10 seconds, then turn it OFF. This refreshes the cellular connection.

3. Restart Your iPhone:
- Hold the power button and slide to power off.
- Turn the phone back on and try opening the game again.

4. Reset Network Settings (if above fail):
- Go to Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings.
- This will erase saved Wi-Fi passwords but can fix network connectivity issues.

If after these steps you still can't log in using mobile data, there might be an account or server verification problem or a temporary network restriction. I can assist you further or guide you to contact official Lineage2M support if needed.

Let me know what you find after trying these!