You can access your account without any port requirements since QuickBooks Online (QBO) is a web-based system. I suggest contacting your internet service provider to check if the QBO site is block or not.
In the meantime, let's consider logging into your QBO account using a private browser so we can isolate this issue. To do so:
Google Chrome: Ctrl + Shift + N
Internet Explorer and Mozilla Firefox: Ctrl + Shift + P
Due to security reasons all the ports are blocked by default. Share the ports numbers which qbo.intuit.com uses.443 port is already enabled but no luck. Please share the all other port numbers which qbo.intui.com site use.
I can refer you to the right department who can help you with QBO ports. We have a separate forum called Intuit Developers, where you can find engineers who can share the process and terms on linking them to Intuit softwares.
Here you can also get assistance with the program's routines, protocols and configurations to login to your account without any issues. We have experts who knows the software components and ports and how they interact with firewalls.
If you have any other questions about QuickBooks, please reach out to me by adding a new comment below. I'll be right here to help and the Community doors is always open for you. Have a lovely week!
I suggest contacting our QuickBooks Support Team. They can help check the different ports you need to unblock the account so can access it. Also, to check if there's a direct way to connect you with our Intuit Developer Support.
Here's how to contact with our QuickBooks Support:
1. Open your QuickBooks Account.
2. At the top right, click the Help icon.
3. Click Contact Us.
4. Under What can we help you with?, enter any concerns.
5. Click Let's Talk.
6. You'll be routed into the Choose a way to connect with us page.
7. Select how you want to contact them and fill in the information.