Networking hardware sometimes requires proprietary configuration files. While OpenVPN uses .ovpn files, some proprietary router firmware (like DD-WRT or specific ASUS builds) may refer to bundled configs as "bins." ExpressVPN provides .ovpn files, but some users mistakenly rename or pack them into .bin archives for bulk flashing.
"Binding" is a security practice that ensures an application only communicates through the VPN tunnel. If the VPN drops, the application stops all traffic immediately, acting as a foolproof "kill switch." Identify the Interface expressvpn bin