Let's log in to your bank's website and authorise QuickBooks to connect with your financial institution (FI).
Once done, go back to your QuickBooks Online account and manually click Update to refresh the connection.
The exclamation point usually means that your bank's website is experiencing:
technical issues
undergoing maintenance
server issues.
This affects the connection between your FI and QuickBooks. This alert should come up with an error. I'd appreciate it if you can add the exact code so I can provide the steps to resolve this.