Linda bought a modem on amazon to save money on rentals at AT&T Uverse. Leo says that's a great idea. Having your own equipment makes it easier to take your business elsewhere should you want to cancel as well.
If everything else is working on that network, then it's clear the laptop is the issue. It's possible that they're using a WPA2 password and the laptop doesn't support that. Since the laptop isn't that old, Leo doesn't think that's it. She is getting signal on the laptop, it's just not connecting to the internet. It could be Internet Explorer. Try another browser like Google Chrome or Firefox. It's also possible that the laptop is mis-configured for the new network. It may also be that malware is causing it, such as DNS Changer.