I have hosted a CMS site in a server S1 and i do not have license.
when i access site from the same hosted server i am able to access Site UI and UI url
But if i acces the from other servers in the same network i am able to access Site UI but UI url giving error "webpage not found"
What URLs are you using? If you lookup the host name from both places you mention, do you get the same result?
site URL : http://SERVERIP.com
UI URL: http://SERVERIP.com/secure/cms