What is 571which comes up when trying to connect bank?

I can help you connect your bank into QuickBooks Online, bewleysblackrock.

Which bank account are you trying to update so I'll be able to check in our system if there are related issues with your bank.

The Banking Error 571 can happen if the bank is not authorized to send to the destination and authenticate you. In the meantime, you can manually import your bank transactions. Just visit your bank's website and pick the date range of the transactions you want to download. Save the downloaded file in a CSV file format. 

You can follow these steps to start importing into the QuickBooks: 

1. Click the Banking or Transactions menu and select Banking.
2. At the upper-right, click File upload.
3. Click Browse to open the CSV file you downloaded from the bank. Open the file.
4. Map the fields and follow the instructions. 

Once done, you can review and categorize your transactions. For the detailed steps, you can use this article on how to manually upload transactions into QuickBooks Online.

Let me know if you have other questions in handling your online banking so I can sort it our for you. Take care and have a great day!