Check your firewall settings and make sure the local web server secure port is not being blocked (https://localhost:####)

It may be you need to read the installation instructions accompanying the expanded install package : in the temp folder of the local administrator user used to install TIA Admin.

Dildz

The "new" TIA Admin is actually trash. The UI is clunky, there is no clear indication of install progress, installs happen silently (and fail silently) & most times I have to install any updates manually.

This morning, I opened TIA Admin & it updated itself - no indication of anything, the icon just disappeared in the task bar when hovering over it after a while. Rebooted & "localhost refused to connect."
Downloaded the latest version from support - install - reboot - wait for services to start - double click TIA Admin icon - same issue.

The worst update client I've ever used hands down.
While the older TIA admin also had it's issues - at least I could use it.

Make sure TLS 1.0/1.1 and SSL 3.0 are not enabled.  I doubt this is the issue.

Is your I.T. cybersecurity group involved in active directory group policy deployment?  If so, ask them why TIA Admin is not able to start.

Look in the windows event logs (run eventvwr.exe as admin) at the time of the last restart where TIA Admin was attempting to launch - slightly delayed after restart.

BenjaminIT

I've done clean installs of TIA on clean installs of windows 11 and often TIA Administrator just doesn't work. The service just keeps repeatedly restarting.

Windows application log just shows the service falling over and starting again and again.

The firewall is off.

I think perhaps it's an issue with the security certificate, but thats just a guess

I've got some installs where its working OK.

I've never figured out what makes it work, or not work.