I've run through the following guide - http://tomatousb.org/tut:configuring-a-pptp-vpn and it's working fine within the LAN.
However when accessing from via the WAN (Using 3g) I can see the packets getting dropped in the logs.
My tomatousb router is setup using DHCP for the WAN interface which is passed to it from an ADSL modem in half bridge mode.
I've tried a few ways of allowing the traffic using iptables but cannot figure out why it's being blocked:
user.warn kernel: DROP IN=vlan2 OUT= MAC=48:5b……… SRC=121.90.xxx.xxx DST=124.xxx.xxx.xxx LEN=64 TOS=0x00 PREC=0x00 TTL=52 ID=46875 DF PROTO=TCP SPT=51305 DPT=1723 WINDOW=65535 RES=0x00 SYN URGP=0 OPT (02040582010303020101080A224E956F0000000004020000)