VPN Error 1 when connecting from my ISP

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ilNebbioso
Posts: 6
Joined: Tue Jan 17, 2017 11:12 pm

VPN Error 1 when connecting from my ISP

Post by ilNebbioso » Tue Jan 17, 2017 11:25 pm

Hello!
I've got a strange behaviour connecting to a SoftEther VPN Server.
My fiber connection is performed by Telecom Italia/TIM ISP, the main operator in Italy, using FFTB technology. Router is configured by my ISP (but I can modify some settings as well).

I'm trying to connect from the internal LAN behind this router to a SoftEther VPN Server which is connected by another ISP.

The problem is: when I connect from my own ISP internet connection I receive an "Error 1" and I cannot connect. While, connecting from others networks (or tethering too) I can connect as well.

Please note:
- I normally use my own ISP internet connection in order to connect also to some OpenVPN Servers without any problem.
- while using my own ISP internet connection, I can succesfully telnet without errors my vpnxxxxxx.softether.net 443 (cursor blnks).
- I'm using a Windows 10 box (full updated) and SoftEther 4.2.2 build 9634 x64
- while switching from my own ISP internet connection and Tethering (and back!) nothing was changed on settings
- my own ISP internet connection does not have any limitation, outgoing firewall or proxy.
- I tried to reinstall SoftEther and removing/readding the VPN virtual adapter too.

Thank you very much for your help and support!

thisjun
Posts: 2458
Joined: Mon Feb 24, 2014 11:03 am

Re: VPN Error 1 when connecting from my ISP

Post by thisjun » Wed Feb 08, 2017 6:16 am

Did you configure port forwarding at server side?

Is the session which success connection to the server in NAT traversal mode?

ilNebbioso
Posts: 6
Joined: Tue Jan 17, 2017 11:12 pm

Re: VPN Error 1 when connecting from my ISP

Post by ilNebbioso » Thu Feb 16, 2017 11:26 am

thisjun,
first of all thank you for your answer!

1) port forwarding: yes, sure. Otherwise VPN could not work with a different Internet connection from the SAME pc.

2) NAT traversal mode: the settings are NOT changed between switching from one connection (not working) to the other one (which works).
BTW, NAT-T is enabled [edit: was "disabled" by my fault].
Last edited by ilNebbioso on Thu Mar 02, 2017 9:28 am, edited 1 time in total.

thisjun
Posts: 2458
Joined: Mon Feb 24, 2014 11:03 am

Re: VPN Error 1 when connecting from my ISP

Post by thisjun » Thu Mar 02, 2017 7:06 am

NAT-T is enabled in default setting.
Did you really disable NAT-T?

ilNebbioso
Posts: 6
Joined: Tue Jan 17, 2017 11:12 pm

Re: VPN Error 1 when connecting from my ISP

Post by ilNebbioso » Thu Mar 02, 2017 9:28 am

thisjun, hello and thank you for your reply.
No, I'm sorry. NAT-T is enabled (my fault). I'm going to correct my answer.



thisjun wrote:
> NAT-T is enabled in default setting.
> Did you really disable NAT-T?

thisjun
Posts: 2458
Joined: Mon Feb 24, 2014 11:03 am

Re: VPN Error 1 when connecting from my ISP

Post by thisjun » Thu Mar 16, 2017 5:45 am

I think your ISP blocks the TCP traffic. So, please try to change the port number or ask to the ISP.

ilNebbioso
Posts: 6
Joined: Tue Jan 17, 2017 11:12 pm

Re: VPN Error 1 when connecting from my ISP

Post by ilNebbioso » Tue Apr 18, 2017 1:35 pm

@thisJun,
teorically I agree with you. But, if I do:

telnet vpnxxxxx.softether.net 443

I receive a blinking cursor (it seems to be connected) also from my own ISP too.

ilNebbioso
Posts: 6
Joined: Tue Jan 17, 2017 11:12 pm

Re: VPN Error 1 when connecting from my ISP

Post by ilNebbioso » Mon Apr 24, 2017 11:24 am

thisjun wrote:
> I think your ISP blocks the TCP traffic. So, please try to change the port number
> or ask to the ISP.


Any feedback to my latest answer, please!?

thisjun
Posts: 2458
Joined: Mon Feb 24, 2014 11:03 am

Re: VPN Error 1 when connecting from my ISP

Post by thisjun » Thu May 18, 2017 5:53 am

I think your ISP may use stateful packet inspection on the firewall.
https://en.wikipedia.org/wiki/Stateful_firewall

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