This is what “IP Addressing” is all about, and how it works-
AND why you MUST assign a STATIC IP address to your computer BEFORE you do any “Port Forwarding.”
The “default” setup for computers and routers is to use “Dynamic IP Addressing”.
With this method, everything is automatic.
Your computer doesn't have an IP address permanently assigned to it. Instead, when it boots up it sends a signal out onto your network, looking for a "DHCP Server".
Your router has a DHCP server in it, so it responds and assigns an IP address to the computer from a "pool" of addresses that are available.
If you have another computer, it will go through the same process when you turn it on, and it will be assigned the "next available IP address".
And so on for all the computers on your network.
This method is especially useful for large installations like offices where there may be hundreds of computers. Instead of having to assign addresses to each one, and keep track of who has what number, the DHCP server takes care of all that automatically.
The IP address assigned to any one computer may CHANGE over time, depending on what the "next available" number is when it contacts the DHCP server and asks for an address.
This is OK for most networks, because the IP address a computer is using normally doesn't matter, just as long as it has one, and it's unique- no other computer is using it.
When you do something like "port forwarding", the router HAS TO KNOW the IP address of the computer that the port is forwarded TO so it can send the data to the right place.
You enter the IP address of the computer that is going to be running your game server, or Azureus or your web server or whatever in the port forwarding setup, and the router sends all the data coming in on that port to THAT IP address.
If the IP address of the computer CHANGES, because it got a different address from the DHCP server when it booted up, the router won't know WHERE to send the data, and the port forwarding will FAIL.
YOU have to PERMANENTLY assign a SPECIFIC address to the computer that's going to be running whatever the ports are forwarded for, by entering it in the TCP/IP Network Properties in Windows, ON THAT COMPUTER.
This is called a "STATIC IP Address" because it NEVER CHANGES.
Now when the computer boots up it doesn't have to ask anything for an address, because it already HAS its address, permanently assigned.
The router will never have to worry about where to send the data for the port forwarded program because it NEVER CHANGES.
So the FIRST step in doing port forwarding is to assign a permanent STATIC IP address to your computer.
Anything else, and the port forwarding will likely FAIL.
This is important, EVEN IF YOU ONLY HAVE ONE COMPUTER connected to your router.
Yes, it’s likely that with one computer, it will always receive the same IP address from the DHCP server, so the number may not change.
There is ANOTHER reason why it’s important to assign a STATIC IP address to the computer anyway.
SOME routers may FAIL to forward ports to an IP address which is included in the router’s DHCP server address “pool”. That is, a number which the router KNOWS was assigned automatically, and MIGHT change if a different compuuter asks for an automatic number.
So it’s important to assign a STATIC IP address which is OUTSIDE this “DHCP address range pool”, so the router doesn’t get worried about it changing.
It’s not that complicated, and hardly even hurts when you do it, and it helps insure that your port forwarding will WORK when you’re all done. If you DON’T do it, it just adds another layer to the complexity of trying to figure out WHY it doesn’t work.
Read this to find out HOW to choose a Static IP address for your computer:
How to choose a Static IP address?
Then, if your Internet connection stops working because of the DNS Server addresses required by the Static IP setup, read this:
How to find your DNS server addresses?