Need a Little help with PPTP VPN connection issue.

[dnt408]

I have 2 AC68U with Merlin’s 380.67_0 firmware (Let’s call it VPN A and VPN B). They are both setup for PPTP VPN. My machine is a Windows 10 LSTB Enterprise.

When I connected wirelessly in one environment (VPN A), and try to establish a VPN connection to the other one (VPN B), I get an error message of “Error 778: It was not possible to verify the identity of the server” While in that same environment (VPN A) and I try to establish a VPN connection to VPN A, it connects without error.

To rule out the router being the issue, I took my laptop to my company and tried to connect to VPN B. No issue at all.

So maybe it’s the router? To narrow the issue down, I connected laptop directly into the router using the Ethernet port instead of Wireless. No Issue at all.

So I suspect it’s an issue with the router’s wireless setting blocking something. Any idea?

Also here is a strange one. If I’m connected wirelessly (VPN A environment) and connect to my company’s VPN using PPTP (Not an Asus router with merlin firmware), it connects fine. While connected wirelessly to my company’s VPN, I establish a connection to VPN B, it connects fine now.

Here is the log when it connects fine while connected to my company’s VPN

Jul 20 19:22:15 pptpd[5818]: CTRL: Client 12.208.18.134 control connection started
Jul 20 19:22:15 pptpd[5818]: CTRL: Starting call (launching pppd, opening GRE)
Jul 20 19:22:15 pptp[5819]: Plugin pptp.so loaded.
Jul 20 19:22:15 pptp[5819]: PPTP plugin version 0.8.5 compiled for pppd-2.4.7, linux-2.6.36.4
Jul 20 19:22:15 pptp[5819]: pppd 2.4.7 started by steve, uid 0
Jul 20 19:22:15 pptp[5819]: Using interface ppp10
Jul 20 19:22:15 pptp[5819]: Connect: ppp10 <--> pptp (12.208.18.134)
Jul 20 19:22:15 pptpd[5818]: CTRL: Ignored a SET LINK INFO packet with real ACCMs!
Jul 20 19:22:15 pptp[5819]: Cannot determine ethernet address for proxy ARP
Jul 20 19:22:15 pptp[5819]: local  IP address 192.168.1.1
Jul 20 19:22:15 pptp[5819]: remote IP address 192.168.10.2
Jul 20 19:22:15 pptp[5819]: MPPE 128-bit stateless compression enabled

Here is the log when it fails to connect while I’m connected wirelessly in (VPN A environment)

Jul 20 19:24:02 pptpd[5943]: CTRL: Client 73.151.201.159 control connection started
Jul 20 19:24:02 pptpd[5943]: CTRL: Starting call (launching pppd, opening GRE)
Jul 20 19:24:02 pptp[5944]: Plugin pptp.so loaded.
Jul 20 19:24:02 pptp[5944]: PPTP plugin version 0.8.5 compiled for pppd-2.4.7, linux-2.6.36.4
Jul 20 19:24:02 pptp[5944]: pppd 2.4.7 started by steve, uid 0
Jul 20 19:24:02 pptp[5944]: Using interface ppp10
Jul 20 19:24:02 pptp[5944]: Connect: ppp10 <--> pptp (73.151.201.159)
Jul 20 19:24:05 pptpd[5943]: CTRL: Ignored a SET LINK INFO packet with real ACCMs!
...
Jul 20 19:24:31 pptpd[5943]: CTRL: Ignored a SET LINK INFO packet with real ACCMs!
Jul 20 19:24:31 pptpd[5943]: CTRL: Ignored a SET LINK INFO packet with real ACCMs!
Jul 20 19:24:31 pptpd[5943]: CTRL: Ignored a SET LINK INFO packet with real ACCMs!
Jul 20 19:24:31 pptpd[5943]: CTRL: Ignored a SET LINK INFO packet with real ACCMs!
Jul 20 19:24:31 pptpd[5943]: CTRL: Ignored a SET LINK INFO packet with real ACCMs!
Jul 20 19:24:31 pptpd[5943]: CTRL: Ignored a SET LINK INFO packet with real ACCMs!
Jul 20 19:24:31 pptpd[5943]: CTRL: Ignored a SET LINK INFO packet with real ACCMs!
Jul 20 19:24:31 pptpd[5943]: CTRL: Ignored a SET LINK INFO packet with real ACCMs!
Jul 20 19:24:31 pptpd[5943]: CTRL: Ignored a SET LINK INFO packet with real ACCMs!
Jul 20 19:24:31 pptpd[5943]: CTRL: Ignored a SET LINK INFO packet with real ACCMs!
Jul 20 19:24:31 pptp[5944]: LCP terminated by peer (^YoNM-R^@<M-Mt^@^@^C^J)
Jul 20 19:24:31 pptpd[5943]: CTRL: Client pppd TERM sending
Jul 20 19:24:31 pptpd[5943]: CTRL: Client pppd finish wait
Jul 20 19:24:31 pptp[5944]: Terminating on signal 15
Jul 20 19:24:34 pptp[5944]: Connection terminated.
Jul 20 19:24:34 pptp[5944]: Connect time 0.5 minutes.
Jul 20 19:24:34 pptp[5944]: Sent 16 bytes, received 0 bytes.
Jul 20 19:24:34 pptp[5944]: Modem hangup
Jul 20 19:24:34 pptp[5944]: Exit.
Jul 20 19:24:34 pptpd[5943]: CTRL: Client 73.151.201.159 control connection finished

 

[dnt408]

Just an update. Found the issue in my case. I went through each setting and found it was the "NAT Acceleration" causing my issue. Turned it off and my VPN worked again.

Weird considering it didn't work in wireless but worked when connected with the ethernet cable. I would think "NAT Acceleration" would work the same way for both setting.

 

[ColinTaylor]

Thanks for the update, I'm sure there are other people that will benefit from that information.

 

[peraburek]

I can confirm this issue, since I am facing the same problem

I have used MerlinFW since 378.52 in the meantime followed update line all the way to 380.68_4

I have 5x AC68U and 1x N66U, all of the devices are affected

sometimes I can't connect with Android Smartphone anymore to PPTP VPN server running on Asus router with MerlinFW

but I can't connect at all with Win7 64bit laptop to PPTP VPN server running on Asus router with MerlinFW due to "Error 778: It was not possible to verify the identity of the server"

can you please look into this issue, it used to work flawlessly in the past, so it has to be that something has messed up PPTP VPN server, because I didn't had "NAT acceleration disabled"
I know PPTP VPN isn't secure, but it is only used to quickly adjust something in router (web gui) if neccessary or view CCTV stream from time to time

 

[ColinTaylor]

@peraburek The Windows Error 778 is fairly non-specific. For example it can be caused when the wrong username or password is entered.

Can you post the output of the router's syslog at the time the problem occurs.