Generally, the default gateway, the IP below the 255.255.255.0 will end in one. Such as 192.168.1.1 or 192.168.16.1.
If all computers are getting to the Internet check the NIC to see what the default gateway is. If you make the IP address of the "server", it will conflict with the gateway. Not sure what your "server" is. Only an OS will have a DHCP server. If not, use the router as your DHCP server. It is ALWAYS better to use DHCP if possible. You do need to make a static IP for the computer with AC on it.
All in all, it may be best to have someone remote in.
By the way, having AC start up and not be able to find the server is NOT a feature. It is also not a bug. It is a misconfiguration of your network, likely.
