Thank you for reaching out to the Community and telling us about your issue, though I apologize that you are experiencing this.
I am hoping that you can provide us with some more information in order to better assist you.
What instance of Stifel are you trying to connect to? Have you tried resetting the account connection?
If you have not yet tried resetting, here's how you do that.
1. Click on the account from the list on the left of your Quicken.
2. Click on Settings in the bottom right corner of the account register.
3. Click on the Downloads tab at the top of the box.
4. Click Reset Connection.
5. Follow the prompts.
Check back and let us know the outcome!