Can you please check in host file if you mapped IP with host name?
check with your host file and your proxy settings as well. it happened with me where my proxy was blocking my remedy IP.
Looks like issue with only midtier. So when you try to load midtier url (e.g: localhost:8080), it works fine and it does not load page when you try with IP address. so as suggested, you need to update hosts file with ip address entry so that it will resolve the IP address.
secondly, make sure correct AR server name/ip address is configured in remedy midtier server configuration page. otherwise it will result in
ARERR 9280 :
A failure occurred because the name of the server xyz is not in the list of valid mid tier servers.