I am unsure what you mean by external ip and internal ip. But I will try to give you some basic trouble shooting steps to follow.
On the new server, you will need to open up a command prompt. (start/run/cmd)
1. Ping the loopback address.
ping 127.0.0.1
If reply ok, go to 2.
2. Ping that interfaces IP.
ping x.x.x.x
If reply ok, go to 3
3. Ping that interfaces Gateway.
If reply ok, then go to 4
4. From another machine, ping the servers IP.
If no reply is given from 3 or 4, check the subnet mask for the server.
If the subnet is correct on both the server and the client you were trying to ping from, we will need to look at mac address' and route table.
On the server run (still at the command prompt) ipconfig /all
Note the physical address for that interface, write it down.
Next type: route print
Look to see that you have routes for your network in your routing table. If you do not have any routes you will need to build them manually.
Next go to the client machine and run the following command: arp -a
Look to see if the IP address for the server is there. It will also have a corresponding physical address. If the 2 physical address' are different then that is your problem.
To delete the arp entry type in the following
arp -d x.x.x.x. (where x.x.x.x='s the ip of the server)
Then try pinging the servers ip again.
If you still can not reach it then I would start over again, but this time checking the cables and making sure that they are not crossed.
Once you can ping the gateway for the interface of the server, then we should be good to go. The rest will be either in the phycial connections, arp or the routing tables.
Good luck
