Confirm the IIS Manager settings for the Defender Management Portal website.
IS > Expand sites > Select the Defender Web Interface > Right Click Edit Bindings > select HTTPS > edit > verify if Hostname is correct.
Confirm port: no need to use 8080 if you have a certificate uploaded then they are likely using HTTPS which is port 443 and would not use 8080
To enable automatic sign-in to the portal
1. On the Defender Management Portal computer, open IIS Manager.
2. In the left pane, expand the appropriate nodes to select the Defender Web Interface site.
3. In the right pane, under IIS, double-click Authentication.
4. Right-click the Anonymous Authentication option to select Disabled.(possibly only use windows authentication.)