Unable to add new customer, is the server down

Hello there, @malvinnz-outlook.

I want to ensure this is taken care of. First, may I know if you've received an error message? Any information can help us resolve the issue.

In the meantime, let's access QuickBooks in an incognito window and add a customer from there. It's where we can identify if the issue is browser-related.

Use these keyboard shortcuts to launch a new private window:

• Google Chrome: press Ctrl + Shift + N  
• Mozilla Firefox: press Ctrl + Shift + P
• Safari: press Command + Shift + N

If it works, go back to your regular browser and clear its cache. You can also use another supported browser to identify if the issue is browser related.

I've added these articles about adding customer profiles and shipping addresses to their invoices: 

• Add and manage customers in QuickBooks Online
• Add a customer's shipping address to invoices in QuickBooks Online

Let me know if you have other concerns about adding customers to QuickBooks. I'm always here to help. Take care.