The benefit of disabling VPN passthrough is enhanced security by blocking open communication ports through the firewall that otherwise would be open and accessible. The drawback is that a user behind the gateway would not be able to establish a VPN connection, since the required VPN ports are blocked at the firewall.

What is IPsec passthrough?

IPSEC pass through is a technique for allowing IPSEC packets to pass through a NAT router. By itself, IPSEC does not work when it travels through NAT. ... However, many router vendors have developed a “pass through” technique that allows IPSEC packets to pass through NAT without NAT-T support.

Do I need IPsec passthrough?

Your router only needs it if you want to use a VPN that supports IPsec or PPTP protocols. ... OpenVPN and IKEv2/IPsec don't just offer better and quicker encryption; they also tunnel through the NAT on their own, so your router doesn't need a passthrough at all.