What is VPN Passthrough? A 2026 Complete Guide

September 29, 2026 By Nancy William No Comments 8 minutes

Have you ever dug into your router settings and spotted “VPN Passthrough” hidden in a security menu? If yes, you’ve probably wondered what it does and whether you should touch it. 

Most people ignore it because not everyone understands it, and some prefer not knowing. Some enable it thinking it will make their VPN faster or more secure. However, neither conclusion is accurate.

For this purpose, this guide explains what VPN passthrough is, why it exists, whether you need it, and how to configure it properly on your router.

What is VPN Passthrough?

VPN passthrough is basically a router setting. It lets you allow VPN traffic to pass through the router’s firewall and NAT (Network Address Translation) system without being blocked. 

It doesn’t create a VPN connection, doesn’t encrypt your data, and doesn’t hide your IP address. So, it simply lets VPN traffic from a device on your network reach an external VPN server.

For a more non-technical explanation, you can think of it as a security guard. He’s been given orders to let anyone with a VPN badge pass through. So, the guard isn’t providing the VPN; they’re just not standing in its way.

Why Does VPN Passthrough Exist?

If you’re still confused about why passthrough is needed, you first need to understand what NAT does. Let’s dive in: 

The NAT Problem

Your home router uses NAT to let multiple devices share a single public IP address. So, when your laptop sends a request to the internet, the router swaps your device’s private IP. It exchanges it with a public one, sends the request out, and then routes the response back to your laptop.

To do this, NAT relies on port numbers. Every outgoing request gets tagged with a port number. This way, the router knows which device the response belongs to when it comes back.

So, what’s the issue here? 

Some older VPN protocols don’t use standard port numbers. PPTP, for example, uses GRE (Generic Routing Encapsulation). This doesn’t have port numbers at all. When NAT sees GRE traffic with no port information, it doesn’t know what to do with it. The traffic gets dropped, and your VPN connection fails.

VPN passthrough solves this by telling the router how to handle these older protocols.

How Each Protocol is Handled

Types of VPN Passthrough

Most routers that support VPN passthrough offer three separate toggles. These include: 

PPTP Passthrough

PPTP, or Point-to-Point Tunneling Protocol, is one of the oldest VPN protocols. It uses GRE to encapsulate data, which NAT struggles with. 

PPTP passthrough modifies GRE to include a Call ID that functions like a port number. This allows NAT to route the traffic correctly.

TECHNICAL WARNING: PPTP is considered obsolete and insecure. It uses weak encryption (MS-CHAP v2) that can be cracked. If you’re still using PPTP, you should switch to a modern protocol.

L2TP Passthrough

Next is L2TP Passthrough, which is often paired with IPsec for encryption. It uses a Session ID that acts as a substitute for a port number, allowing NAT to track the connection. L2TP passthrough enables this handling.

SECURITY NOTE: L2TP/IPsec is more secure than PPTP but is slower and less efficient than modern alternatives like WireGuard or OpenVPN.

IPsec Passthrough

IPsec (Internet Protocol Security) is a suite of protocols used to secure internet communications. It doesn’t natively work with NAT because it encrypts the packet headers that NAT needs to read.

IPsec passthrough solves this using NAT-T, or NAT Traversal. This means it wraps IPsec packets inside standard UDP packets. NAT can read the UDP header, assign a port number, and route the traffic correctly.

PLEASE NOTE: IPsec is still widely used in corporate VPNs and is considered secure when configured properly.

Do You Actually Need VPN Passthrough?

No, you don’t actually need it, and here are a few reasons why: 

• Modern routers have it enabled by default. So, unless you’ve deliberately turned it off, VPN passthrough is likely already active on your router.
• Modern VPN protocols don’t really require it. WireGuard, OpenVPN, and IKEv2 all handle NAT natively. They don’t need the router to pass through.
• FastestVPN uses modern protocols by default. Our apps use IKEv2 and WireGuard, both of which work seamlessly with NAT without any router configuration.

When Would You Need VPN Passthrough?

There are a few situations where VPN pass through is still relevant:

• You’re connecting to a corporate or school VPN that uses PPTP or L2TP/IPsec.
• You’re using an old VPN client that only supports legacy protocols.
• You’re troubleshooting a connection failure with an older router or VPN setup.

However, if none of these apply to you, you can safely leave VPN pass through alone. Alternately, disable it for better security. We’ve covered some security risks below. 

Is VPN Passthrough Safe?

Even though VPN passthrough itself isn’t dangerous, leaving it enabled when you don’t need it does have a few security risks. Take a look below: 

VPN Passthrough Risks

• Legacy protocols usually have known vulnerabilities. PPTP, in particular, is easy to break. So, leaving PPTP passthrough enabled keeps a door open for a protocol that should be retired.
• Creates a larger attack surface. Every enabled feature on your router is a potential entry point. So, if you’re not using it, disable it to reduce your exposure.
• It comes with no encryption benefit. Passthrough doesn’t encrypt anything. It just allows traffic through. So, if your VPN connection isn’t properly configured, passthrough won’t do much for your security.

Our Recommendation?

If you’re using FastestVPN or any modern-day provider that has WireGuard, OpenVPN, or IKEv2, you can safely disable VPN passthrough on your router. This closes off legacy protocol handling that you don’t need.

However, if you’re using PPTP or L2TP/IPsec for a specific reason, like a corporate VPN, leave passthrough enabled for those protocols but disable the ones you don’t use.

How to Enable or Disable VPN Passthrough on Your Router

These steps vary by router manufacturer; however, the general process is the same. 

First, sign in to your router’s admin panel:

• Open a browser and enter your router’s IP address. 

Common addresses are 192.168.1.1, 192.168.0.1, or 192.168.2.1. Check your router’s manual if none of these work.

• Enter your admin credentials. The default username and password are often “admin” and “admin,” but check your manual or the sticker on your router.
• Navigate to the VPN Passthrough section. For that, look under “Advanced Settings,” “Security,’ or “NAT Forwarding.”

However, the exact location varies.

• Now, find the VPN Passthrough options. 
• You’ll typically see three toggles. These include PPTP Passthrough, L2TP Passthrough, and IPsec Passthrough.
• Enable or disable as needed.
  • If you’re using a modern VPN, then disable all three.
  • If you’re using a legacy protocol, then enable only the one you need.
• Save your changes.

Lastly, the router may reboot.

Common Router Locations

Here are a few Router brands and where to find their Passthrough options:

VPN Passthrough vs VPN Router vs VPN Client – What’s the Difference?

Have you heard of these three terms and often get them confused? Here’s what sets them apart: 

PLEASE NOTE – VPN passthrough is not a substitute for a VPN. It’s just a compatibility feature for older protocols.

Frequently Asked Questions

To Conclude

VPN passthrough is an old router setting or a compatibility feature. It’s designed to solve a specific problem, which is helping older VPN protocols work with NAT. 

However, as mentioned, in 2026, it’s not really necessary. Modern protocols handle NAT natively, and modern routers have passthrough enabled by default anyway.

If you’re using FastestVPN, you don’t need to touch passthrough at all. Our apps use IKEv2, OpenVPN, and WireGuard, all of which work seamlessly. There’s no need for any router configuration with it.

However, if you’re troubleshooting an old VPN setup or connecting to a corporate network that uses old protocols, passthrough is there when you need it. 

Lastly, remember that it’s a compatibility feature, not a security feature. Your actual protection comes from the VPN itself.