We've got a remote location we want to VPN to.

We've been using a Draytek 3200 for load balancing connections in our main office for a while now, and we're very happy with it.

We bought a Draytek 2920 to act as the VPN client/router at the other location. While we're configuring we have both Drayteks on premises.

For testing/configuration purposes our connection looks like this:

PC 1 (Main Network) - 192.168.50.110
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Draytek 3200 - 192.168.50.4
Wan 1 (Fibre leased line)
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Internet
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Draytek 2920 - 192.168.100.4
Wan 1 (ADSL Backup internet)
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|
PC 2 - 192.168.100.110

So, even though they're in the same office, the VPN is still going out of the office.

After reading Draytek's articles on LAN-LAN VPN we tried their configuration and found it didn't work.

Using the old fall back of trying to be as simple as possible for the sake of testing we then configured things like this:

3200 -
Common Settings
Dial In, Idle timeout 0, VPN Dial-out Through Wan1 Only,

Dial In settings
PPTP
username: fred
password fred
PPP Auth: PAP/CHAP
VJ Compression: On

TCP/IP Network Settings
Remote Network IP 192.168.100.0

And the reverse on the other side (Dial in becomes dial out, Always on, same user, Remote Network IP 192.168.50.0

No connection occurs.

SSH into the 3200 and log -ct reports a PPP session starting every 5 minutes.
log -wt reports:

(The ConfReq/Nak/Rej Ids go from 0x00 through 0x0B, but I truncated due to post size limitations.

Code:

24:53:01 >>>>PPTP (VPN-0) Len = 18 Protocol:LCP(c021) ConfReq Identifier:0x00 Authentication Type: PAP Magic Number: 0x1 ## 24:53:01 <<<>>>PPTP (VPN-0) Len = 15 Protocol:LCP(c021) ConfRej Identifier:0x00 Protocol Field Compression Address/Control Field Compression Call Back: 06 ## ... 24:53:04 >>>>PPTP (VPN-0) Len = 18 Protocol:LCP(c021) ConfReq Identifier:0x0B Authentication Type: PAP Magic Number: 0x1 ## 24:53:04 <<<

It looks like an issue with authentication failure. I think.

We've tweaked, restarted, reset, changed and twiddled. Hoping someone has an idea!
Have made sure none of the PPTP ports are forwarded to other servers. The Remote access services are enabled.