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Unless you are willing to pay for commercial internet service which costs at least $100 - $150 a month, your consumer-priced internet service would not allow you to have a static IP address. The IP address in home/consumer internet service is dynamically reallocated by your ISP's DHCP server and, therefore, your public IP address would change frequently.

Having a static IP address is important because DHCP IP address is like having your telephone number changed everyday by your telephone company because they don't have enough telephone numbers to go around.

The DHCP server is a computer sitting on your ISP's network. Your ISP would have configured your modem to refer to their DHCP server to obtain an IP address. Therefore, the modem, not your home computer, is allocated a public IP address by your ISP.

In order to function as a public server, your home computer would need to subscribe to DDNS (dynamic domain name system).

"Dialup VPN"
Some ISPs provide you with a "broadband dialup" service, where your computers are given concocted private LAN address to help them stinge on public IP addresses. A piece of software, called a dialer, is installed on your computers. They give it a nice impression by calling it VPN (virtual private network) even though it is not exactly a VPN (because it can only operate within their own network routes) and they would convince you that it is safer for you to operate on their "VPN".

In such a case, you have to call your ISP and inform them that you need to install your own wireless router because their address-stinging scheme would not be able to operate over your wireless router and there is no way they can morally deny you the privilege of using wireless computer connections at home (unless you live in a 4th world authoritarian regime and your government is also your ISP).

They would then change the mode, of their DHCP to your modem, from private network to public network. Diagrammatically, in the sequence of connections, that is a change from
public network > public-private NAT/DHCP by ISP > private network to modem

public network > ISP's DHCP public network to modem > public-private DHCP/NAT by modem > private network to computers.

If your ISP demands an increase in monthly fees and you are not willing to pay that increase, you may stop reading now because without the change, you will not have an effective means to make your home computer visible as a server to the world wide public internet. You need the public-private NAT configuration to be in your hands.

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