UPDATE: Router error logs show:

LCP Time-out 0

I'm not sure how to correct this. The Lan-to-Lan profiles are set to -1 Idle Timeout (for the remote branch).

I have a PPTP VPN running between two Draytek 2820 routers. They are setup that one dials out to the other one.

Main Practice - 192.168.1.0/24
Branch        - 192.168.3.0/24

I have then set (on the Branch) router the following route:

192.168.1.0/24

If I then request a server running on 192.168.1.1 from the Branch, it correctly routes through VPN tunnel. If I request the branch server at 192.168.3.1 it correctly routes to the local server without using the VPN tunnel.

I have temporarily disabled the firewall on both routers, and made sure that QoS is disabled.

The Main Practice internet connection is ~30mb down / ~10mb up, and the Branch connection is ~5mb down / ~2mb up.

Anything over the VPN tunnel runs pretty slowly (VNC, Remote Desktop and Terminal Emulators). However, if I dial using the Windows VPN wizard, creating a connection from the laptop to the Main Practice - everything runs quickly.

I'm looking for possible causes, and/or ways of further diagnosing the issue. Any help would be greatly appreciated!

UPDATE: In summary, when I connect within the Branch and try and access a host that's within the Main Practice it works, but slowly. If I then dial the VPN on my Windows 7 laptop whilst still connected to the Branch network, it's fast.

Main Practice Branch Practice

Routing Table from Branch Router

Key: C - connected, S - static, R - RIP, * - default, ~ - private
*            0.0.0.0/ 0.0.0.0          via 126.256.126.103   WAN2
C~      192.168.1.99/ 255.255.255.255  directly connected   VPN-1
S~       192.168.1.0/ 255.255.255.0    via 192.168.1.99     VPN-1
S~       192.168.2.0/ 255.255.255.0    via 192.168.1.99     VPN-1
C~       192.168.3.0/ 255.255.255.0    directly connected    LAN2
C    126.256.126.103/ 255.255.255.224  directly connected    WAN2

Routing Table from Main Practice

Key: C - connected, S - static, R - RIP, * - default, ~ - private
*             0.0.0.0/         0.0.0.0 via 81.139.64.1,   WAN2
S        81.137.176.1/ 255.255.255.255 via 81.137.176.1,   WAN2
*         81.139.64.1/ 255.255.255.255 via 81.139.64.1,   WAN2
C~      192.168.1.204/ 255.255.255.255 is directly connected,    VPN
C~        192.168.1.0/   255.255.255.0 is directly connected,    LAN
S~        192.168.2.0/   255.255.255.0 via 192.168.1.204,    VPN
S~        192.168.3.0/   255.255.255.0 via 192.168.1.203,    VPN

Connection Details (from Branch Router)

Connection Details (from Main Practice Router)

IPERF.exe Output