For months I have been connecting my HSBC accounts but it perpetually says the connection has expired. Has anyone else experienced this? Does anyone know how to fix it?

Thanks for sharing your concern with us, adrian-foster.

I recommend logging in to your bank's website to check if there are maintenance updates. If there are any changes, you'll need to disconnect your bank account from QuickBooks. Then, you can add it again, like a new bank account. 

Here's how to disconnect your bank:

1. Go to the Banking menu and then select Banking.
2. Choose the HSBC bank account.
3. Click the Pencil icon on the blue tile.
4. Select Edit account info.
5. Place a checkmark in the Disconnect account on save box.
6. Click on Save and Close.

Here are the steps to reconnect the account:

1. Click Add account.
2. Search for HSBC.
3. Choose HSBC Bank (UK) - Business Banking - Other Accounts.
4. Click Continue and follow the on-screen instructions.

Aside from that, you can also manually upload the bank transactions to bring them into QuickBooks. I'll guide you how:

To download transactions from your financial institution: 

1. Log into your bank’s website.
2. Follow the steps to download your transactions using an acceptable file format. 
3. Set the date range.
4. Follow any on-screen instructions to finish the download.
5. Reformat the file if necessary. 
6. Save the file to your computer. 

After that, you can upload the file to QuickBooks. In your left navigation pane, go to Banking and then select Upload transactions.

For detailed instructions, see the second to fifth steps through this article: Manually Upload Transactions into QuickBooks Online.

Once downloaded, you can edit and categorise your transactions in the For Review tab. It helps you ensure your financial records are accurate. For more information, I encourage you to check out this article: Categorise and match Online Bank Transactions.

Keep us updated by clicking the Reply button if you have other banking concerns. Doing so helps us to provide accurate solutions.

Thanks for your quick response. I have been on to my bank website and connected maybe a dozen times over the past 3-4 months. It's always the same, it connects and then says it has expired.
A few months ago, I followed the instructions you have just given, deleted the account and reconnected and it was a disaster! It downloaded all the transactions again so the information in quickbooks is meaningless. It doubled my turnover! I had to pay my accountant extra to manually calculate my income and expenditure for the year for my tax return. 
I have a really simple business that I kept on a spreadsheet for years until the government introduced MTD.

I have been really busy this year and cannot spend the time on this for much longer.

Welcome back, @adrian-foster. I appreciate you for sharing your sentiments when trying to connect HSBC bank in QuickBooks. This isn't what we expect you to experience. 

Since you've already tried the steps shared by my colleague without luck, I'd recommend you contact our Customer Care team at this point. They can help check to identify what's causing this to happen. We also have a tool that we can use to refresh the connections between QuickBooks and your bank manually. 

Moreover, they can also submit a request to investigate this error you're getting whenever necessary. 

For future reference, read through this article to learn more about how to handle duplicates should you encounter it again. 

Thanks for coming back for more support, @adrian-foster. I'd be here to answer your next posts here in the Community.