Need help with bridging (newbie question)

[Emelya]

Dear SE community, please help me to configure my SE server. My machine has two physical network adapters: LAN-Ethernet interface for INTRANET and a cable-modem for INTERNET. I want to use cable-modem for announcing server in DDNS (softether.net) and as interface for connecting users. Then users should automatically switch to LAN interface to be able to reach INTRANET. I don't know how to do it. I created the virtual hub, connected it with the server's local bridge to cable-modem interface, activated Secure NAT and added the static route as follows: 0.0.0.0/0.0.0.0/LAN interface IP-address. But it doesn't work. Users can connect to cable-modem interface but then they don't change the interface. They still located on cable-modem (assigned IP-address from cable-modem) and are not able to reach intranet. In system my cable-modem interface has higher priority (lower metric) than LAN interface. But I can't change the priority, because I want the server to announce itself via cable-modem. Please help me to solve the problem as I'm very poor in networking, and sorry for my English. My machine runs Windows XP.

[solo]

Disable SecureNAT, remove the bridge and instead bridge it to the LAN interface.