I tried many times to back up my iPhone but fails although I have the biggest iCloud storage space 2 TB and the mobile is connected to WiFi al the night while the mobile screen is closed. Any solutions?

Backing up your iPhone to iCloud for the first time can indeed be a time-consuming process, as it involves transferring all your data, settings, and apps to Apple's cloud servers. If you're experiencing this for the first time, here are some tips to help you through the process:

1. To begin the backup process, make sure your iPhone is connected to a Wi-Fi network and plugged into a power source. Also, ensure that you have enough available iCloud storage to accommodate the backup.
2. The initial backup can take a considerable amount of time, depending on the amount of data you have on your device. It may range from a few minutes to several hours, especially if you have a large amount of photos, videos, and other data to back up. It's essential to be patient and avoid interrupting the backup process.
3. During the backup, it's crucial to keep your iPhone connected to the internet via Wi-Fi. Using cellular data for this process may incur additional charges and might not be as stable as Wi-Fi.
4. Make sure your iPhone remains connected to a power source throughout the backup process. Backing up large amounts of data can drain your battery quickly, and you don't want the backup to get interrupted due to a low battery.
5. As the initial backup might take a significant amount of time, a good idea is to start it before going to bed. Connect your iPhone to Wi-Fi, power, and open the backup page, then leave it undisturbed for the whole night. When you wake up in the morning, you should find that the backup has likely completed successfully.
6. A stable and robust internet connection is crucial for a successful backup either over mobile data or Wi-Fi. If your internet connection is unreliable, the backup process might pause or fail, leading to potential data loss.

Remember, subsequent backups after the initial one will typically be faster because only new and modified data will be uploaded to iCloud. This is known as incremental backup, and it helps save time and data usage in the future.

By following these guidelines, you'll ensure a successful and hassle-free initial backup to iCloud and safeguard your important data for future use.