There are a couple of ways to identify the main computer. If AC is on the server, named server with IP address of 192.168.1.1, you could identify it as either "server" or "192.168.1.1"
If you use the former, occasionally AC decides that's not good enough, it wants the IP address and you have to change it to 192.168.1.1. Now occasionally, if the IP addresses are not done by the server (DHCP server) the IP address of the "server" will change and it might be 192.168.1.2 and it cannot be found using your initial IP address (....1.1)
You can solve this by going to the network adapter properties under the TCP/IPv4 settings and change it from "Obtain IP address automatically" to "Use the following IP address" If you were to put 192.168.1.1 in that setting, it would hopefully forever be locked into 192.168.1.1 and you could address it as such. (You also have to set the subnet mask (often done automatically but generally 255.255.255.0(or 255))and the default gateway should probably be your router should be the IP address of your router if that is giving out the IP addresses (=DHCP server.)If your server is the DHCP server, it should be fixed as to the IP address and this should not be a problem.
I don't know why AC sometimes prefers the IP address to the name of the computer, but it does. It helps if that number will not change.
