The most likely reason the employee cannot access the CRM software is that their computer is not connected to the local network, as access to local network hosted applications requires a connection to that network. If the internet was down but the local network was still operational, they should still be able to access local network hosted applications. If the computer was in airplane mode, it would disable all wireless connections, including the local network, but the key factor is the connection to the local network itself. The presence of a firewall may block specific incoming or outgoing traffic but would not typically prevent access to applications hosted within the same local network unless incorrectly configured.