Skip to content

Demystifying VPN Passthroughs: The Complete Expert Guide

If you‘ve done any research on virtual private networks (VPNs), you‘ve likely encountered the term "VPN passthrough" before. But you may still be wondering — what exactly does a VPN passthrough do? And when do I need one?

Don‘t worry, you‘re not alone. Many people get tripped up on the technical jargon around passthroughs despite using VPNs every day.

As an online privacy guru, let me explain what a VPN passthrough is, why it matters, and how to set one up on your home network. By the end of this guide, you‘ll be a VPN passthrough expert!

What Is A VPN Passthrough? A Simple Definition

A VPN passthrough is a specific feature on routers that allows VPN traffic to bypass the router‘s Network Address Translation (NAT) system and pass through to the VPN server.

NAT technology, found on most modern routers, hides the details of devices on your home network and allows them to share a single public IP address for privacy and security.

But this can cause issues for some VPN protocols in establishing a connection back to their servers. A VPN passthrough explicitly approves certain protocols like L2TP and PPTP so that NAT systems allow their traffic rather than blocking it.

Some Key Facts:

  • Passthroughs are built into most routers produced in the last decade
  • They act as exceptions to let select VPN traffic through NAT defenses
  • Common types include L2TP passthrough, PPTP passthrough, and IPsec passthrough

Without a properly configured passthrough, VPN services relying on older protocols may struggle to maintain a steady connection as NAT repeatedly blocks them. The passthrough keeps things running smoothly.

Now that you know what a VPN passthrough is in simple terms, let‘s explore more of the nitty-gritty details around how this technology works…

How Does A VPN Passthrough Actually Function?

To really understand what purpose a VPN passthrough serves, we need to dig one level deeper into what happens when your device attempts to connect to a VPN server:

  1. You launch your VPN client app to secure your internet traffic through an encrypted tunnel.

  1. The client tries to establish a connection by sending traffic to the external VPN server.

  2. By default, your router sees this outward-bound traffic and attempts to block it using NAT as an assumed security measure.

  3. BUT – thanks to your pre-configured VPN passthrough rules – the router identifies these packets as legitimate VPN activity, and allows them to pass through unimpeded.

  4. With the handshake and data transfer unblocked, your system negotiates the VPN tunnel and secures your web browsing.

That simple action of classifying the VPN setup process as "safe" is all your passthrough needs to do. NAT remains active otherwise, but permits your VPN to coexist without interference.

Think of it like getting an exclusive backstage pass for your VPN at an exclusive club. The bouncer (NAT) questions everyone by default, but the passthrough gives your VPN VIP status so it can come and go as needed. Without it, your VPN would constantly get held up and disrupted!

The Difference Between A VPN Passthrough & VPN Router

Now, related technology you might come across is a VPN router. What separates it from a simple VPN passthrough?

  • VPN Passthrough: A software feature that enables select protocols to traverse NAT and maintain connectivity. Requires no additional hardware.

  • VPN Router: A physical networking device with VPN software built-in to encrypt ALL connected traffic by default via a virtual interface.

In everyday terms:

  • A passthrough just gets your VPN working on an existing router

  • A VPN router encrypts everything behind it as dedicated hardware

For home use and small offices, a basic VPN passthrough performs the necessary job. But large enterprises may opt for a full VPN router solution to put a cloaking shield around the entirety of their local network traffic.

Who Needs A VPN Passthrough?

If you utilize any modern VPN services leveraging protocols like OpenVPN, IKEv2, or WireGuard, you likely have no use for an explicit VPN passthrough.

Why? These updated protocols already come prepared to bypass NAT filtering without any special help. Enabling a passthrough would be redundant since they avoid NAT interference on their own.

You would still potentially benefit from a passthrough if:

  • You have an older or free VPN service relying PPTP, L2TP and similar outdated protocols
  • Your networking hardware uses antique operating systems and drivers
  • You experience frequent VPN disconnections indicating possible NAT conflicts

However, for privacy and performance reasons I always recommend selecting a premium VPN solution utilizing OpenVPN or IKEv2 where possible. Both protocols have widespread compatibility and can withstand NAT handling without passthroughs configured.

The VPNs that still require passthroughs are typically free or extremely cheap. And unfortunately free VPNs have major trust issues when it comes to protecting user privacy and data. Whenever feasible, go for a reputable paid solution like [Editor‘s Choice VPN] instead.

But if you DO need to accommodate legacy VPN gear, read on for how to activate that passthrough…

Step-By-Step Guide To Enabling A VPN Passthrough

Many newer consumer routers actually have VPN passthrough functions enabled right out of the box. But some models still require diving into the settings to flip that switch.

Here is exactly how to enable a VPN passthrough on most any home router:

  1. Look up your router‘s administration page IP address. Typically 192.168.1.1 or 192.168.0.1
  2. Enter that IP into your browser bar to access admin settings
  3. Log in using your admin username and password
  4. Navigate to the VPN or other related security section
  5. Find the checkbox options for enabling PPTP, L2TP, and/or IPsec passthrough support
  6. Check boxes to activate desired protocols, save changes
  7. Connect to your VPN as normal and traffic should flow!

Steps might vary based on your router make and model. Check your owner‘s manual if the above does not work.

Once enabled, VPN passthroughs require no additional management or input from you. Set it and forget it!

Occasionally you still need to configure port forwarding rules even WITH a passthrough, depending on the VPN type. Double check router manuals to determine if manual ports like 500/UDP or 1701/TCP should be routed for common VPN connectivity requirements.

To Summarize…

While VPN passthrough importance has decreased slightly thanks to wider compatibility with modern protocols, it remains a useful trick to facilitate legacy VPNs.

Main takeaways:

  • Passthroughs provide an exception path through NAT that otherwise blocks VPN traffic
  • This keeps your encrypted tunnel steady on finicky old protocols like PPTP
  • Separate from dedicated VPN router hardware products
  • Generally not needed on OpenVPN/WireGuard/IKEv2 VPN apps
  • Quick router setting change when required

I hope this insider look has helped explain what purpose VPN passthroughs serve, why they matter, and how to configure them when required. Never hesitate to reach out with other VPN questions!

Related reading: