How to Fix VPN Error 806

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Diana Todea

Chief Editor

Fix

8 min. read

Updated on September 16, 2025

VPN Error 806 occurs when your computer successfully connects to a VPN server but cannot complete the VPN connection. This happens because something, often a firewall or router, is blocking the VPN’s data packets, specifically the GRE protocol used by PPTP connections.

The good news is that you can resolve this error with a few straightforward adjustments. Below are the step-by-step solutions.

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What is VPN Error 806?
PPTP VPN Requirements
How to Fix VPN Error 806
Preventing VPN Error 806 in the Future
FAQ
Wrapping Up

What is VPN Error 806?

VPN Error 806 is an error code that indicates your device started a VPN connection but couldn’t complete it. The full error message states something like:

“A connection between your computer and the VPN server has been established, but the VPN connection cannot be completed… Error Code 806. The most common reason is that at least one internet device (for example, a firewall or router) between your computer and the VPN server is not configured to allow GRE (Generic Routing Encapsulation) protocol packets.”

In simpler terms, the VPN server is reachable and credentials may be correct, but VPN traffic is being blocked mid-way. PPTP VPNs, a common VPN type on Windows, use two things to function: TCP port 1723 for control, and the GRE protocol, ID 47, for encapsulating data. If either of these is blocked, often by a router or firewall, the connection stalls.

This error is related to other connection issues, such as VPN Error 800 where the VPN server cannot be reached at all, or VPN Error 789 which signals authentication problems. Unlike those, Error 806 is not about credentials or server reachability. It is specifically about blocked protocols.

PPTP VPN Requirements

Requirement	Details
TCP Port 1723	Must be open for VPN control traffic, handshake.
GRE Protocol 47	Must be allowed through firewalls or routers. GRE carries VPN data.
PPTP Passthrough	Router must allow GRE. Some routers have a PPTP Passthrough setting, enable it.

How to Fix VPN Error 806

Before diving into firewall settings, check your basics. Ensure your internet connection is working and consider restarting your devices. A simple router reboot or PC restart can clear temporary glitches. Once that’s done, proceed with the targeted fixes below.

1. Open Port 1723 in Windows Firewall

One common cause of Error 806 is Windows Firewall blocking the VPN’s communication port. PPTP VPN uses TCP port 1723, which needs to be open.

Steps to open port 1723:

Open Windows Defender Firewall, Advanced Settings.
Go to Inbound Rules > New Rule.
Choose Port > TCP and enter 1723.
Select Allow the connection.
Apply to all profiles, Domain, Private, Public.
Name it, for example “PPTP VPN TCP 1723”, and finish.

2. Allow GRE, Protocol 47, through Firewall and Router

GRE, Generic Routing Encapsulation, is identified as protocol number 47. Without it, PPTP VPN will not work.

On Windows Firewall:

Go to Inbound Rules > New Rule.
Choose Custom Rule.
Under Protocol, select GRE, 47.
Allow the connection, apply to profiles, and name it.

On the Router:

Enable PPTP Passthrough in the admin panel.
If hosting a VPN server behind the router, forward port 1723 and ensure GRE is allowed.

3. Configure Router, If Hosting a VPN Server

If your VPN server is behind a router:

Log in to your router’s admin panel.
Go to Port Forwarding or Virtual Server.
Forward port 1723 TCP to your server’s local IP.
Enable PPTP passthrough so GRE traffic is allowed.
Save changes and reboot the router.

If you are just a VPN client, you can skip this step. But if you manage your own VPN server, failing to set this up will always result in error messages like Error 806 or even VPN Error 619, which indicates the server terminated the connection due to communication issues.

4. Temporarily Disable Firewalls or Antivirus

Security software sometimes blocks VPN traffic.

Steps:

Temporarily disable Windows Firewall or third-party antivirus firewall.
Try reconnecting to the VPN.
If it works, re-enable security and add exceptions:
- Allow TCP 1723 and GRE 47.
- Add your VPN app as a trusted program.

If your VPN still will not connect after these checks, it is worth comparing with other scenarios such as VPN connected but not working, which also points to traffic being blocked even when the tunnel is technically up.

5. Update Your Router’s Firmware

Old router firmware can mishandle GRE and PPTP traffic.

Check your router model and firmware version in the admin panel.
Download the latest firmware from the manufacturer’s website.
Update it through the router interface.
Re-enable PPTP passthrough or forwarding after the update if needed.

6. Try a Different VPN Protocol

If Error 806 persists, it may be because your ISP or network blocks PPTP. Since PPTP is outdated, consider switching to another protocol:

L2TP/IPsec
OpenVPN
IKEv2
SSTP

These do not use GRE and are more secure. Many VPN apps let you change this in settings. If switching helps, you will avoid PPTP specific issues like Error 806, but might still encounter other problems such as VPN Error 720 if your client network settings are misconfigured.

Preventing VPN Error 806 in the Future

Keep firewall rules, TCP 1723 and GRE 47, active.
Ensure PPTP passthrough stays enabled after router reboots.
Keep routers and Windows updated.
Use modern VPN protocols when possible.
On restrictive networks, switch to OpenVPN or IKEv2 to avoid GRE issues.

For more general fixes, check our complete guide on VPN not connecting. If the tunnel connects but drops midway, see VPN Error 807 for guidance on server interruptions.

FAQ

What causes VPN Error 806?

VPN Error 806 usually means the VPN tunnel starts but cannot pass traffic because GRE packets are blocked. This can be caused by Windows Firewall, antivirus software, or more often the router between you and the VPN server. Unlike VPN Error 800, which means the server cannot be reached at all, Error 806 means the server was reached but the tunnel could not be completed.

How do I fix VPN Error 806 on Windows?

To fix it, make sure the right port and protocol are open:
In Windows Firewall, create a rule for TCP port 1723.
Create another rule to allow GRE, protocol 47.
On your router, enable PPTP passthrough or forward TCP 1723.
Disable antivirus or firewall briefly to test, then add permanent VPN exceptions.
These steps typically resolve the issue. If it still fails, switching to another protocol avoids the GRE problem entirely.

Can a router firewall cause VPN Error 806?

Yes. Many routers block GRE by default. If you are connecting to a VPN server inside your home or office, the router must allow GRE protocol and forward port 1723. Otherwise, Error 806 will appear. In fact, misconfigured routers are also responsible for related codes like VPN Error 619 where the server drops the connection unexpectedly.

Which ports or settings should I check?

Check the two essentials of PPTP:
TCP port 1723, used for setting up the VPN connection.
GRE protocol 47, carries the actual encrypted traffic.
Also verify router firmware is updated, and that PPTP passthrough is enabled. If these are not set properly, you will get persistent 806 errors.

Is VPN Error 806 specific to PPTP VPNs?

Yes. PPTP is the only major VPN protocol that depends on GRE. That is why you do not see Error 806 when using OpenVPN or IKEv2. If you consistently run into 806 and your network does not allow PPTP, switching protocols is the easiest fix.

How does Error 806 compare to other VPN errors?

Error 806 is about blocked GRE traffic. Other codes point to different issues:
VPN Error 789 which is an authentication or security layer problem.
VPN Error 800 which means the client cannot reach the VPN server at all.
VPN Error 720 which indicates a TCP/IP configuration problem on the client.
If you see multiple codes, resolving each depends on identifying whether it is connectivity, authentication, or configuration related.
VPN Error 809 which indicates a blocked network path to the server (often IPsec ports or ESP filtered).

Wrapping Up

VPN Error 806 is frustrating but fixable. It happens because PPTP VPN traffic is blocked, usually GRE or port 1723. By allowing these in your firewall and router, updating firmware, and switching protocols if needed, you can resolve the issue quickly.

If problems persist, you might be dealing with a deeper connectivity problem like VPN connected but not working or even unrelated service specific issues such as Error 1006 Access Denied when accessing blocked sites. But in most cases, carefully following the steps above will get your VPN back online.