Why is my bank not connecting to QuickBooks Online?

https://quickbookhelpdesk.com/blog/quickbooks-banking-connection-errors/

Common causes include incorrect banking credentials, internet connection problems, browser issues, temporary bank maintenance, or security verification requirements. Bank connection issues in QuickBooks Online are usually caused by incorrect login credentials, browser problems, internet connectivity issues, temporary bank maintenance, or account authorization changes. Most of these issues can be resolved without major effort. Checking your internet connection, verifying your banking credentials, refreshing the connection, clearing your browser cache, reconnecting the account, and keeping your browser updated can solve many bank feed problems.