I am not able to add funds using internet banking

I don't know what you mean by internet banking.

If you mean by logging into your internet banking then that's not possible.

Some banks have the option to buy a giftcard directly from your internet banking app and use the code to redeem it to your apple id, but that's different.

You can use the payment methods that appear here.

Add money to your Apple ID balance - Apple Support

Credit/Debit card and other payment methods based on your region.

Generally speaking the best way to access a bank account is by using the debit card that is connected to it.

Read and follow the article linked above.

Additionally:

Payment methods that you can use with your Apple ID - Apple Support