One possible solution is to uninstall TT 2024, download the current version (www.InstallTurboTax.com) and reinstall it EACH TIME you want to use TT. I don't know how often TT updates www.InstallTurboTax.com but you might want to give it a try. Keep track of the version and components numbers in the "About" menu item of each install.
My strong guess is that update URL embedded in the TT code is incorrect--hence page not found. The only way to fix that is to have TT users reinstall a newer version (with the correct URL) or issue a patch that users will have to install separately from TT. Given that Update is not working, it can't be fixed by updating.
Or maybe the update website is broken. But that (I think) would be relatively straightforward fix.
