If you can already access the IEvD via IP address, then the next step is usually outside of IEvD itself.

You need to make sure the FQDN resolves to the IEvD IP address through DNS. Once DNS resolution is working, you can access the IEvD using the hostname instead of the IP.

Things I would check:

• Create or update the DNS A record for the desired hostname.
• Verify that the IEvD certificate includes the FQDN if you're using HTTPS.
• From a client machine, test DNS resolution using nslookup <fqdn> or ping <fqdn>.
• Ensure any firewall, reverse proxy, or load balancer configuration is using the same hostname.

If the FQDN resolves correctly but IEvD is still only reachable by IP, then I'd look at the web server/certificate configuration rather than the network settings.

In my experience, IEvD does not typically require a separate setting to "switch from IP to FQDN"; the important part is having proper DNS resolution and matching certificate configuration.

Hope this helps.