I have dynamic IP and my ISP is Cox Communications.
I've been trying the ipconfig/release and renew method and it doesn't work. Shutting off modem / modem+router for 15 minutes doesn't work either.
I use cable modem and a router with an Ethernet cable connected between them since there are like 4 people using the same networks at my house.
Is there any other I can do?
Thanks for your question MMPretzel.
First I'll explain the difference between the internal and external IP addresses.
The Internal address is the IP assigned, usually by your Router, to the computers on you Local Area Network (LAN). That is the address you release and renew at the command prompt using ipconfig.
The External IP is the one you see on our home page. It is the one people often seem to want to change. This is your Wide Area Network(WAN) or Internet IP Address. In reality, there is no improvement in security by changing the External IP but many people seem to want to change it anyway.
To change your External IP with a Cable Modem, you need to change the MAC Address of the first device connected to it. In most cases that would be the MAC address of the Router. Most currently manufactured Routers have the ability to clone the WAN or Internet MAC Address. The easiest way is to clone the MAC address of a computer on your LAN. You can discover the MAC Address of each computer by typing "ipconfig /all" at the Command Prompt. It will be displayed as the Physical Address and will be six sets of two alpha/numeric characters. It will be displayed as follows. xx-xx-xx-xx-xx-xx
This is important. Once you have changed the MAC address of the first device connected to the Cable Modem, you MUST do a cold boot of the Cable Modem for it to accept the change. In most cases, this requires the removal of the power cord from the Cable Modem and the backup battery if it has one. I recommend doing this with the Router powered off as well. When you power on the Cable Modem, you need to give it about 60 seconds too boot before powering on the Router. Then power on the Router and give it about 30 seconds to boot. Then boot the computers and they should be online with a new External IP Address.