can no longer access cable company tv online since last iosupdate

There have recently been many reports of a broad range of new problems on this support site about the latest release of Safari v15. It is included in the downloads for Big Sur and Catalina. If you are experiencing these problems, you can use another browser such as Firefox or Chrome and they will work for you until a newer version of Safari is released.

I have read here that Apple's support people have a link to reinstall Safari and that doing so often fixes the problem. You might check with them.

Incidentally, it is not an iOS update. Macs run the Mac OS. iOS is a completely different operating system for iPads and iPhones.

Does Safari 15 have IP Relay? If it does, you may have to disable it to view a service providers content. They usually don’t allow access through a relay or VPN.

I’m not able to check myself at the moment.