Having issues to connect bank account for several weeks. Before it was working fine. I need help and fix this. I tried different browsers & I report the issues every day.

Hello, christoph3.

Here are the following scenarios why you're unable connect your bank account:

• The bank may not be a participating bank. 
• Your bank might not connect to all types of accounts (for example, personal accounts vs. business accounts).
• Bank is having a system maintenance.
• Some banks have multiple names on our list. You might want to check and select the correct one, or try all possible bank URL.

What you can do is contact your bank to check if for any maintenance update or request to establish a connection with QuickBooks. 

If everything is good from your bank's side, you can follow these steps to search for the correct bank using the URL:

1. Go to the Banking or Transactions on the left panel.
2. Select Link account or Add account. Note: You won’t add an account, you just need the listed URL.
3. In the Connect your bank or credit card to bring in your transactions field, enter the URL listed for your bank.
4. Follow the on-screen instruction to connect your account.

I'm adding this article for reference: What to do if you get a bank error or can't download transactions in QuickBooks Online.

You can also add the name of your bank and other details in the comments below. This way, I check our records for any investigations. Thank you in advance.