@Erin Ding-MSFT Thanks for the reply. I appreciate the attempt to help.
What's the version of your Office?
The version of Excel is 16.0.5134.1000
Unfortunately I have no ability to install or remove updates on this laptop, because it's centrally managed.
Can you insert this URL as a hyperlink to Excel file and open it successfully?
If I try one of the URLs as a hyperlink I receive the same error message shown in the second image. "Unable to open...."
What's the browser are you using? Please change the default browser.
The browser would be whatever is built into excel. I believe that's some hybrid of internet explorer. I changed my system default from internet explorer to Edge. Made sure all browsers and Excel were closed and then retried. There was no change in behavior. Still getting the error message.
You could also try to create a new blank .xlsx file, then go to Data>From Web and enter a URL that is out of the "target web server" to see if there is the error.
I had previously done this with the same website, but tried three different website that prompts for the user certificate. They all had the same problem. I tried a website that doesn't require a user certificate and it works correctly.
Besides, is there any third-party security software installed on your computer before this issue occurs? Please turn it off temporarily to have a check.
The computers are centrally managed and locked down pretty tightly, there are multiple third-party security tools running on the computer and I have no ability to turn them off. I checked the logs for the ones I can, and I don't see any of them reporting that they are blocking the connections. Since the connection will work temporarily if I click the Here link to start a new session. Or if I File Open the excel file from the web server I doubt they're the issue. The issue seems to be with the way Excel is handling the initial hand shake with the web server.