If you are able to connect via 3G but not the same local network then it is most likely and issue with multiple subnets on your local network, or possibly multiple internal IP addresses being used on the local computer.
Are both your iPhone and computer on the same internal subnet? (First three values of the IP the same.) They should be if you are connecting to the same router.
Does your router perhaps have two WiFi networks associated with it? The second one is usually a "guest" network that cannot connect to the "main" network, but again, it would be using have a different IP block / subnet.
The other possibility is if you have another network adapter on your computer that is bound to a different IP address that the iCamSource is picking up, and the connection logic is getting confused by multiple IPs on the computer.
If you could go to
http://whatismyipaddress.com/ from the computer running the iCamSource and e-mail support@skjm.com what it says your external IP address is then I can attempt to look it up in the Broker Server logs and hopefully troubleshoot the problem.
Please be sure to reference this forum post in your e-mail.