Starting point- you know how to get into your router's settings and browse through the various sections and tabs.
There are 2 meanings of static IP that are being talked about together.
Everything on the internet needs a unique IP address (like "220.127.116.11") so that it can have 2-way conversations.
Your ISP may assign you a static IP address which will be the same for years or it may change every week or so or any time you turn off you modem. You can see it in your router setup screen.
Each device you use on your network needs to have an internal IP address to talk to the router. A typical $50 router has 256 IP addresses (that all start with "192.168") with a few reserved already. Usually there is a "handshake" and the router assigns it an IP address but if you turn off the laptop or tablet, when you turn it on it will shake hands again and get a random IP address which might be the same or different.
In your router settings, this is called DHCP. You might set your router to use a pool of IP numbers from 100 to 200.
Once you have picked that range, you can make devices have a fixed IP inside the network but you have to stay out of the DHCP range, so you might assign it "11". You have to make sure not to make 2 devices have the same number (eg: keep track in a notebook or in a special file).
Suppose you want to set up "Remote Desktop" to a particular desktop on the network and it says that the port is "3389". In the router under "port forwarding" you would then forward port 3389 to local IP "11" (which might be shown as something like "192.168.1.11" )
When you start remote desktop from a laptop in a coffee shop, you will enter the IP address of your house (that you wrote down), then the remote desktop program sends packets with port 3389 so the router knows to forward them to 192.168.1.11 which is always
the desktop computer. If the house computer used a DHCP address, the port-forwarding wouldn't know which device to talk to from one day to the next.
For $10 or $20 per year, you can get a dynamic DNS provider so that you don't even need to write down your internet IP address and it stays the same (eg: "neilshouse.dyndns.com
") even when your IP changes. Inside your router it should show which companies they work with (eg: dyndns). For the cheap price you don't get a full domain, just a sub-domain. For more money ($50 per year) you can get normal sounding domain name like "neilshouse.com
" You can now create your own subdomains with different port numbers so that different subdomains correspond to different items in your house, like "birdhousecam.neilshouse.com
". You would forward different ports to different fixed IP numbers in your house.
One place you can trip yourself up is that laptops have a wireless network device and a physical plug device. If you set up a fixed IP address when it is plugged in using an ethernet cable, it may become DHCP with a different IP address when you are using it wirelessly.