PPTP VPN on my NAS Synology VPN Server through HUB2 not working

[#1]

Hi

I am trying to use a VPN server hosted on my Synology NAS box. I am finding that accessing the VPN locally works, but through the internet not. I have Fibre broadband via Plusnet.

I have a static IP, Plusnet firewall set to OFF. 

I have a port forward setup for PPTP TCP port 1723 to my NAS box. I can't enter the IP of the NAS it is a drop down but it is finding the correct IP. (NAS BOX has its own IP address not DHCP).

I tried pining the TCP port but it fails. I have the HUB 2 router setup with allow ping. I have also tried it with the HUB2 firewall set to LOW and OFF.

On the client side I have tried it both on Android and Windows clients, both fail.

Ideas welcome.

Thanks

Andy

[#2]

Moderators Note

This topic has been moved from Broadband to Tech Help

[#3]

@Andy001z  ISTC there's a predefined rule for PPTP VPN forwarding. The problem is that you need to not only forward TCP port 1723 but also the GRE protocol. I dont think you can specify that manually but the predefined rule does it.

I dont have my HUB 2 connected at the moment, but if you have trouble finding the standard rules, post back and I'll fire it up...

[#4]

@MisterW 

As far as I can see the Hub Two does not have any predifined rules.

Dan 

[#5]

Hello Andy,

Presumably you want to do the same as described in this link

< https://kb.synology.com/en-au/SRM/tutorial/What_is_port_forwarding#x_anchor_id7 >

and do it in your Plusnet router but you don't know the ip address of your NAS.

Go to < http://192.168.1.1/firewall.htm > in your Plusnet router where you will see all connected devices on your network.

Disconnect them all accept the NAS and there you will see the ip address you need to add the port forward rules to.

Not the most elegant way I admit, but it's a start.

One idea.

Regards..

[#6]

As far as I can see the Hub Two does not have any predifined rules.

@Dan_the_Van  I must be wrong, maybe I was thinking on one of the earlier routers. Maybe the Hub 2 is 'clever' in that it opens the firewall for GRE when its detects a connection on Port 1723.

Is there any config option in the Firewall section for a VPN helper or Alg ?

[#7]

Hub One had predefined rules, all you see with a Hub two is:-

May have to use openVPN as an alternative

Edit: just SIP alg

[#8]

No I know the IP address of the NAS server, that all seems fine.

[#9]

@MisterW 

I am using a PPTP VPN server on a windows 10 desktop and connecting from a old Samsung smart phone via mobile hotspot

FWL Port Forward Server(192.168.10.220) TCP 1723 accepted a new connection from 85.255.nnn.nnn 

TCP    192.168.10.220:1723    85.255.nnn.nnn:63551    ESTABLISHED

HTH

[#10]

In that case all that demonstrates all that's needed is the port 1723 forwarding to the nas. Assuming the nas has a pptp server running...

[#11]

A thought, is there a firewall that needs setting up on the NAS drive to allow inbound connections for 1723

If there is a linux shell I would use the netstat command to see if port 1723 is listening.

[#12]

I went and tried the NAS router wizard which included port forwarding. Setup and no change to status. Still not working.

I can see in the Hub 2 log that port forwarding is working in that it shows 

FWL Port Forward Server(192.168.1.25) TCP 1723 accepted a new connection from 31.9.x.x

but nothing after this.

On the NAS VPN server log, it shows no connection inbound or any other helpful info.

Regarding someone suggesting TELNET to the Hub to check settings, it seems the HUB 2 telnet service is not running.

So frustratingly close.

[#13]

If you see the inbound port forward connection that suggests the issue is with the PPTP server.
It is possible to use telnet as a test to see if a port will accept a connection, the syntax is
telnet (IP address of the device) 1723
you either get connection refused, no connection or a open command prompt box perhaps with a few random characters

[#14]

If you see the inbound port forward connection that suggests the issue is with the PPTP server

@Andy001z  is the NAS set to allow pptp connections from any public ip ?

Sounds like it might be restricting to the local lan

[#15]

@MisterW morning.

In addition to your post, I also wonder if the NAS IP config was setup manually rather than using DHCP and a default gateway has not been assigned?

Is there is a linux shell on the device or the ability to use telnet or ssh, netstat might help to see what going on?

netstat -r list the default gateway IP Address

netstat -antu | grep 1723 see if port 1723 is listening and if a connection is being attempted or established