You're going the wrong direction in this troubleshooting.
I am attempting to access my text messages on the web, from a web browser. Doesn't matter right now what kind of device. But to be complete, I am using Firefox or Chrome browser on a Linux computer. This worked fine last week and for many years prior. It does not work today because someone made a change on the web site. I initially connect using the URL https://vtext.com, which redirects to the link you referred me to in the troubleshooting step. I gave you the result. Someone turned off this service on the web. I need it back. If I could do this on my phone, I would, but I can't for the reasons I've already given.