Dual network (LAN + WLAN) application issues

I have a dual network setup on my PC (XP SP2 /w CFP 2.4) as following:
A. NIC connected to a switch then to an ADSL modem for dial-up ADSL internet connection
B. USB wireless adapter linked to wireless router also connected to the ADSL modem

The wireless setup ( B) is mainly used for connection between several of my computers, forming a WLAN, but also allowing it to access Internet. The fixed LAN connection (A) is for use of having more stable and direct Internect connection. I would have the wireless to connect itself after boot and then execute the ADSL dial-up, through this way all the apps would use the fixed LAN connection as primary and the wireless connection would be only standing by unless being specifically triggered (ex. incoming VNC connection).

Here comes the problem: Windows Live Messenger 8.1 would only connect when I only have the wireless on, but would not connect when I have both connections on or only the dial-up ADSL connection on. The application would just stuck in the “Logging in” screen, no error message shown.

I have played around with the Application and Network monitor settings, along with checking the log, thinking it was simply a setting issue, but nothing seemed different when connecting through pure wireless setup to the dual network setup. The network diagnose function inside Windows Live Messenger also showed that the connection is good and the system passed all connection tests.

Without CFP, the connection status under Windows Live Messenger would state the following under two different setups (which seems fair to me):
a. connect using wireless: “Connected to the Internet via wireless, connected under none-UPnP, limited NAT access”
b. connect using dual network: “Connected to the Internet via wireless, connected under direct access”
With CFP, the results are still as above except that (b) would only state “Connected to the Internet via wireless” but not the latter sentence because it is not connected to MSN server.

Above might have just been Windows Live Messenger bugs, but what made me really curious and think it shuold be related to CFP is:

  1. Windows Live Messenger wouldn’t connect even if I set the firewall settings to “Allow All” or simply terminating the firewall instance. I had to completely remove CFP to make it work again under the dual network setting.
  2. If I have both wireless and ADSL connected, and then disconnect the ADSL connection, leaving only wireless, all the Internet access is cut off (it would still be able to access Internet under this setup without CFP installed). I have tested the Internet access via pinging host names and IP addresses, both having no result.

I have checked the FAQ and haven’t found any similar issues for reference, any solutions and/or instructions for diagnose are welcome, thanks!

My guess would be that CPF only recognizes the default gateway learned via the wireless NIC. So how to make CPF aware of the second default gateway of the LAN NIC?
Try adding a trusted zone for the LAN NIC …