L2TP VPN for work not connecting

[MTSW]

Previously used the older Google WiFi as my home router and had no issues with connecting to the VPN. However recently, after upgrading to the newer Google Nest router, I am not able to connect to the L2TP VPN. Is there any fix to this?

[olavrb]

What error do you get, what does the logs of the VPN client say?

I use VPN daily with Cisco AnyConnect and Wireguard without any problems. 2x Nest Wifi router (AC2200) in wireless mesh.

[MTSW]

Hi there.

Whenever I try to connect to the VPN, it just says:

"Can't connect to L2TP. The network connection between your computer and the VPN server could not be established because the remote server is not responding. This could be because one of the network devices (e.g. firewalls, NAT, routers, etc) between your computer and the remote server is not configured to allow VPN connections. Please contact your Administrator or service provider to determine which device may be causing the problem."

It worked fine last week when I was still using the older Google WiFi as the router, so I am suspecting that it could be due to the newer Google Nest Router. I'm using mobile tethering as a temporary solution so there is no issues with the VPN server either.

[olavrb]

There should be no difference in how Google Wifi and Nest Wifi works in regards to this.

What does the logs say? What VPN client do you use?

• It should say what FQDN or domain it's trying to reach and on what port + protocol.

Could be DNS, could be ISP, could be the VPN server or the firewall in front of it not accepting traffic coming from you for whatever reason. Could be a lot of things. But without logs/ more info, it's hard to know where to start looking.

[MTSW]

I completely understand that this issue could be due to a multitude of reasons, but I'm trying to eliminate the possible causes one at a time so I do not have to rely on whatever limited mobile data I have.

The logs says that I "dialed a connection name L2TP (name of the VPN) which has failed. The error code returned on failure is 809.". 

As for the VPN client, I am using a Windows (Built-In) VPN provider. All the information I have is of the server address, sign-in type, username and password. 

DNS Wise, I tried changing it from the ISP one to 1.1.1.1 but it doesn't work either. I have asked my colleagues and they have no issues connecting to the VPN from their home WiFi network, so that eliminates issues with the VPN server. As for the firewall for the server, I have no idea since I am not the one managing it.

Not sure if this helps, but I can connect to my personal VPN service with the WiFi network.

[olavrb · Accepted solution]

• https://docs.microsoft.com/en-us/windows-server/remote/remote-access/vpn/always-on-vpn/deploy/always...
• https://docs.microsoft.com/en-us/troubleshoot/windows-client/networking/l2tp-ipsec-vpn-client-connec...

You could try PowerShell "Test-NetConnection" to domain and port to see if a connection can be made. If it doesn't work behind Nest Wifi, try with the laptop connected directly to the modem, bypassing Nest Wifi.

[MTSW]

I tried connecting the laptop directly to the modem to bypass the Google Nest Router and it wasn't able to connect to the VPN either. I tried using tracert in command prompt and there were some timeouts in between the ISP and the host server, so I was guessing that it could be issues with the ISP side. 

Just got off the phone with the ISP and they said it was an error on their side. They managed to unblock the IP address of the server for me so everything works now. Thanks for your help thus far.

[Jeff]

Hey, MTSW.

It's been a while since we had back and forth here. I just wanted to check in to see if you were all set on this or if there's anything else you needed. If you still need some input, just let me know.

Thanks.

[Jeff]

Hi, everyone.
Just one quick final check in here since activity has slowed down. We'll be locking the thread in the next 24 hours, but if you still need help, I would be happy to keep it open. If there's more we can do, just let me know.
Thanks.

[Jeff]

Hi, everyone.
As we haven't had any activity here recently I'm going to go ahead and close the thread. If you have more to add, feel free to start a new discussion.
Thanks