Airport Express creating a new network after changing ISPs

I have an Airport Express that I have used for decades, and it worked fine. However, when I changed ISPs it stopped working. When I restarted it, it set up a 2nd network. Not sure how to get it set up again. Any ideas on setting it up ahain. Yes, I know it is not Apple-supported, being old.

[Re-Titled by Moderator]

Original Title: Express making new network