try the ..:7443/arcgis/adminpanel and look at the log files.
if this is not working, then look in the portal's log files located here: <arcgisportal site location>\logs\<your machine name>\portal
There should be some errors that make it a little more clear what's going on.
you may need to talk to your network person at some point.
if you just want to look, in windows, using a command prompt or powershell, and check the network configuration.. "ipconfig /all" will tell you what the machine name is and what ip is and confirm with the network person if it's right.
ipconfig /all
<returns something like>
Windows IP Configuration
Host Name . . . . . . . . . . . . : TEST-Machine-N1
Primary Dns Suffix . . . . . . . : test.machine.com
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . : test.machine.com
pwc.uis
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Intel(R) PRO/1000 MT Network Connection
Physical Address. . . . . . . . . : 00-50-65-FA-74-FC
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
IPv4 Address. . . . . . . . . . . : 60.80.170.144(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 60.80.170.129
DNS Servers . . . . . . . . . . . : 190.160.240.20
NetBIOS over Tcpip. . . . . . . . : Enabled