What is VPN Passthrough?

VPN allows users to establish a private connection between a device and a server. You can use a VPN through an app, like most commercial VPNs, or by configuring the router with VPN settings. Routers today have the functionality to allow VPN configuration, but many older routers have problems dealing with VPN traffic.

What is VPN Passthrough

That’s where VPN Passthrough comes in. It tells the router that the traffic is allowed to leave and enter your router. In this blog, we’ll cover why VPN Passthrough is needed in detail and how you can enable it in your VPN router.

Why VPN Passthrough is Needed

VPN works with several protocols, such as PPTP, IPsec, and OpenVPN. Routers have a NAT (Network Address Translation) table that they use to translate local IP to public IP and deal with outbound traffic. It needs to know that the traffic leaving the router is allowed. Modern routers are versatile when it comes to dealing with VPN traffic, but older routers are not.

VPN Passthrough refers to the feature that allows your device to establish a VPN connection with a remote server using the PPTP and LT2P/IPsec protocol. The two said protocols are old; hence, routers are unable to work flawlessly with them. FastestVPN supports both protocols, so an old router might not allow you to establish a connection while using PPTP or LT2P.

VPN encapsulates your data with an outbound IP address. The router receives the request and tries to apply the NAT process,but it cannot understand the type of traffic that’s passing through. VPN Passthrough

GRE (Generic Route Encapsulation) is used to communicate between two virtual points. It encapsulates data and ensures its delivery while it travels through multiple nodes on the internet. With VPN Passthrough, PPTP uses GRE with a call ID attached that forgoes the requirement of a port number that NAT uses.

Similarly, IPsec uses NAT-T, which encapsulates data into a UDP packet. The UDP protocol works with NAT. It allows the NAT to recognize it and gives it a port number through which to forward the packet.

How to Enable VPN Passthrough in Router

It should be said first that if you’re using a different protocol than this feature is not needed. In fact, protocols such as IKEv2 and OpenVPN are superior to PPTP and LT2P/IPsec in every way, and FastestVPN comes packed with all of them.

However, if you find yourself dealing with PPTP or LT2P, then you can enable the option in the router. In most cases – if not all – this option should be enabled by default. Settings menu and navigation varies from manufacturer to manufacturer. Below is an example of a TP-Link router page.

Enable the relevant options under VPN sub-heading under the Basic Security tab.

Enable VPN Passthrough in Router

If you have a different, then you ought to have similar settings that shouldn’t be hard to find. Login to your router with the credentials. If you don’t remember the credentials, then you might be using the default credentials. Refer to the back of the router to find the username and password. It’s also a good idea to change the default password while you are in the settings, for reasons you can read in our Wi-Fi security blog.


For most people, this is going to be a non-issue simply because there are more advanced protocols that seamlessly work with NAT. FastestVPN uses the IKEv2 protocol by default in its Windows and iOS app.

Unless you are trying out the protocols, we recommend sticking to IKEv2 and OpenVPN for establishing a VPN connection.

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