PPTP VPN Server on RT-N66U

[MarkyPancake]

I'm trying to set up my router for VPN for my Android devices and can't get it to work.

When I'm connected to the home wireless network I can connect to the VPN I have created (key icon in Android notification bar), but no data is sent or received, which from what I've read is not unusual behaviour under this circumstance.

When I'm connected to a different wireless network and connect to my VPN it tries for a while and then eventually just says 'disconnected' and doesn't work (no key icon in notification bar).

Should I be using the default VPN IP range of 192.168.10.x or should I set it to the same IP as my DHCP addresses, but outside of the DHCP range obviously? I've tried both IPs and get the same behaviour as above.

The MRU and MTU default is 1450 and my ISP is 1500. Is the default value okay or should I tweak this.

As it stands, I'm currently using the PPTP VPN settings as they appear when you enable this option.

I was hoping to be able to use this VPN whilst out of the country instead of a third party one.

 

[ColinTaylor]

I've been using it OK for some time now with the same setup as you. I'm just using the default settings (apart from creating a user name and password).

What messages do you see in the syslog.

 

[MarkyPancake]

This is from the log when I tried it via a family member's BT broadband (I've crossed out their IP address):

Aug 4 16:54:47 pptpd[1946]: CTRL: Client 86.x.x.x control connection started
Aug 4 16:54:47 pptpd[1946]: CTRL: Starting call (launching pppd, opening GRE)
Aug 4 16:54:47 pptp[1947]: Plugin pptp.so loaded.
Aug 4 16:54:47 pptp[1947]: PPTP plugin version 0.8.5 compiled for pppd-2.4.7, linux-2.6.22.19
Aug 4 16:54:47 pptp[1947]: pppd 2.4.7 started by admin, uid 0
Aug 4 16:54:47 pptp[1947]: Using interface ppp10
Aug 4 16:54:47 pptp[1947]: Connect: ppp10 <--> pptp (86.x.x.x)
Aug 4 16:55:18 pptp[1947]: LCP: timeout sending Config-Requests
Aug 4 16:55:18 pptp[1947]: Connection terminated.
Aug 4 16:55:18 pptp[1947]: Modem hangup
Aug 4 16:55:18 pptp[1947]: Exit.
Aug 4 16:55:18 pptpd[1946]: CTRL: Client pppd TERM sending
Aug 4 16:55:18 pptpd[1946]: CTRL: Client pppd finish wait
Aug 4 16:55:23 pptpd[1946]: CTRL: Client 86.x.x.x control connection finished

It didn't work via my work's wireless network either, but I just put that down to our firewall security, as things are locked down pretty tight at work.

 

[ColinTaylor]

http://pptpclient.sourceforge.net/howto-diagnosis.phtml#lcp_timeout

It might be a mismatch of the MPPE Encryption settings. I have mine set to MPPE-40 and MPPE-128, and Authentication set to Auto. On my android phone I have MPPE enabled.

Can you try again from your phone over 3G (Wi-Fi disabled)? Make sure you have a strong 3G signal though otherwise you will see similar messages about timeouts.

 

[MarkyPancake]

I've unselected the No Encryption option under MPPE Encryption in the firmware and already have PPP encryption selected on my Nexus 5 and it connects to the VPN via my phone's mobile data, but still nothing.

I've even tried lowering the MRU and MTU to 1400 and that has made no difference either.

 

[MarkyPancake]

I've tried lowering the MTU to 1392 and it still just hangs when trying to do things that need data, such opening google.co.uk in the browser.

I've gone back through the log and consistently things like this appear when I'm connected:

Aug 4 20:49:04 pptpd[2390]: CTRL: EOF or bad error reading ctrl packet length.
Aug 4 20:49:04 pptpd[2390]: CTRL: couldn't read packet header (exit)
Aug 4 20:49:04 pptpd[2390]: CTRL: CTRL read failed
Aug 4 20:49:04 pptpd[2390]: CTRL: Client pppd TERM sending
Aug 4 20:49:04 pptpd[2390]: CTRL: Client pppd finish wait

I've just connected to bestukvpn.com on my Nexus 5 and it works fine, but my own one doesn't.

 

[MarkyPancake]

I've tried setting my VPN IP pool to the same as my DHCP IP, but using a range that is no where near my DHCP addresses and still nothing.

I've tried lowering the MTU to 1400 and then down in increments of 20, after reading about trying this, and I got to 1340 and still nothing.

There aren't that many options in the firmware, so I don't know what I'm missing.

I've tried specifying the authentication and when set to MS-CHAPv1 my Nexus 5 fails to connect to the VPN. It does connect when set to MS-CHAPv2, but the problem remains.

 

[MarkyPancake]

Finally got it working!

I tried adding my ISP's DNS servers manually to the VPN settings and my Nexus 5 connects and works.