How VPN Passthrough Works (And If Your Router Has It)

If you’ve bitten the bullet on one of the major VPN services, you probably have access to some pretty robust protocols. Generally speaking, most of them will work out of the box, without having to change any router or Internet settings. But what happens if you’re using a VPN that relies on an existing protocol and you’re having issues with your connection? In this case, a VPN passthrough is probably something you should go by on a first name basis. The aptly named router setting allows certain VPN protocols to pass through the firewall. Simply put, it works a bit like an employee ID card by helping the router recognize specific data packets associated with the service you’re using.

No shame if you’ve never heard of this feature. Unless you run a custom configuration or stick with an older protocol, most routers these days automatically recognize VPN traffic. However, you may want to confirm if this feature is manually enabled through the router’s admin panel, as it may pose a small security risk if left unchecked.

A VPN passthrough is a holdover from the days when VPNs relied on different protocols. It all comes down to what is commonly referred to as NAT, or network address translation. The router’s NAT reads information about incoming and outgoing connections to determine which traffic gets the green light and which is banned. Since VPN relay helps the router identify the “hidden” connection, it allows VPN clients to connect unhindered to a server outside the core network.

If you’re launching a VPN to stream geo-blocked content (a smart way to use the service), the connection is likely facilitated by the WireGuard protocol, which already works with most modern routers. A VPN passthrough isn’t really necessary since the router simply receives all the NAT information it needs from the protocol by default. Still, routers may have trouble recognizing older protocols like PPTP, which is the main reason why VPN passthrough remains a reality.

While a premium VPN is worth it because these settings are no problem, there are several reasons to look into passthrough setups. Some people are still using older VPN setups, in which case reviewing these options is a good first troubleshooting step. Or, you may want to close it for security reasons. Either way, the process is relatively simple.

If you’re not sure if you have this feature, start by doing a quick Google search for your particular model. Is everything clear? Then go ahead and navigate to your router’s admin panel. Launch any Internet browser, copy the router’s IP address from the device’s network settings and paste it into the address bar. After entering your router credentials, look for Advanced Settings (name may vary depending on router models). There you will find VPN relay preferences for a variety of existing protocols.

Depending on your perspective, knowing what a VPN passthrough is may seem like useless knowledge. After all, it’s overkill for most modern VPNs, so why bother? Although the security implications may be negligible for most users, this feature leaves some small gaps in your network. For example, the archaic PPTP protocol has its share of vulnerabilities, including a faulty authentication system and poor encryption. Leaving the relay open and “collecting dust” can expand your attack surface, so if you don’t need this feature (like when you’re already using WireGuard or OpenVPN), it’s really best to turn it off completely.