i am having pppoe connection and my isp providing dynamic ip address in the range 180.148.x.x.
Also i am using dc++ hub on LAN without connecting internet with
ip = 10.40.100.100
subnet = 255.255.255.0
gateway = 10.40.100.1
few days ago i changed my LAN gateway from 10.40.100.1 to 188.8.131.52 by doing this i am able to connect dc++ hub while internet is connected
but if changes the ip 10.40.102.100 then i am not able to connect dc++ hub while internet is connected
you need to change your gateway back to 10.40.100.1, on your ISP's network this has to stay the same always since it is a physical router on their network and if your computer does not know the correct IP of the gateway that router cannot tell traffic where to go.
A computer's gateway must be on the same subnet. The gateway address is used when a computer determine's that the remote host it is trying to connect to is not on the same subnet. When it makes this determination, it sends the packets to the default gateway. The computer (TCP/IP) host, does this by the way of a process called ANDing. More information on the topic of routing packets through a network: http://www.itgeared.com/articles/1054-how-ip-packets-are-routed-on-local-area/