I can help you with connecting your personal account to QuickBooks Self-Employed.
May I know the specific error you had when trying to connect your account? This way, I can gather enough resources and look into the message you're getting.
As an initial step, you can connect your account through a private window. In most cases, an unexpected behaviour with QuickBooks happens due to the stock cache of the regular browser you're using. To save you time, you can use either of these keyboard shortcuts:
If it works fine, I recommend going back to your original browser and clear its cache to start fresh.
Moreover, you can use another supported and up-to-date browser to narrow down the result.
Once your account is linked to QuickBooks successfully, you can check out this link on how to categorise your downloaded bank entries: Categorise transactions in QuickBooks Self-Employed.
Please leave a comment below if you have any other questions about connecting an account in QuickBooks Online. I'm always here to help. Have a good one!
Thanks for getting back to us with additional details on your concern, @Clock1. I'm happy to provide some workarounds you can do base on the error code you've mentioned.
The error 571 will likely occur when there are active pop-up blockers. You can disable the pop-up blockers on your browser and try to connect again to fix this issue.
I'd also like to know which bank account are you trying to update. This way, I'll be able to see if there are any related issues with your bank.
If you're still not able to connect your bank account, I suggest to manually import your transactions. Here's how:
I've added some screenshots for additional reference:
Moreover, you can read through this article when your ready to assess your transactions: Categorise transactions in QuickBooks Self-Employed. This also contains sub-article to add bank rule once the issue is solved.
Kindly post here again for an update on what happens after performing the steps I've mentioned. I'll be right here if you need further help. Have a good one!