If you are trying to access your VS admin website via its FQDN name (e.g. http://server.domain.com:1024) try and see is the server’s name change has been reflected on the DNS too.
You could also try and access the VS admin website via its IP address (e.g. http://192.168.0.1:1024).
If the above solution works simply update your DNS records in order to reflect the new IP<->FQDN mapping.
I hope this helps.