If you must transmit a file over an insecure channel, one way to prevent its contents from being seen by someone who might intercept it is to:

use a complex file name that will only be understood by the recipient.

connect to the network from a remote location using a vpn.

encrypt the file before transmission.

make sure there is a firewall in place.

connect to the network from a remote location using a VPN.

Explanation:

VPN stands for virtual private network, it allows computers to establish a secure connection through an encrypted tunnel for exchanging data between two end points when communicating through insecure channels like the internet.

this would start to sound a little like mortal combat

a local network will allow everyone in the office to share the printer.