It seems you dont have visibility to that URL or you can't resolve the DNS (the name of the domain)
In your host file:
C:\Windows\System32\drivers\etc\hosts
Add and entry with the IP of the url (IP number of the server check it in the SAP LOGON) following by the domain and save it.
http://pl1pa273.corio.com:8000
assuming 201.242.10.123 is the IP address:
201.242.10.123 plpa273.corio.com
If this doesn't work, check if you have any proxy configurated, this is not an ABAP issue is IT.
Regards
