Introduction.
First of all let me explain you what is NAT. Network Address Translation (NAT) is the process where a network device, usually a firewall, assigns a public address to a computer (or group of computers) inside a private network. The main use of NAT (Generally Speaking) is to limit the number of public IP addresses. Althought there are many types of NAT, the well-known on this game are the the Strict, Moderate and Open NAT types.

If you play osu! (or any other P2P based multiplayer game), you should consider setting up a port forward for it to better your online gaming experience.

There are several advantages to setting up a port forward for osu!, for example:
- Not getting dropped from games
- Better quality voice chat (in game)
- Less lag
- Improved connection
- Easier to play with friends / join lobbies
- Overall enhanced online experience
...

Note:
This will not speed up your internet speed!
So if you have a very bad internet connection open ports will not fix this "speed problem".
A few words about each type of NAT in osu!
As the title says, I will explain you in a few words the main diffrences of Strict, Moderate and Open Nat.

•Strict NAT: With this kind of NAT you will be able to connect only with players who have their NAT type opened. Also searching for games will take more time. At 90% you will be kicked when a host rotation comes up and also don't forget that lags will be possible.

•Moderate NAT: With this kind of NAT, you can connect up with people who have either Moderate or Open NAT. Searching for games with this kind of NAT will take some time, but not as much as Strict. Lags wil be less than Strict to.

•Open NAT: With this kind of NAT, you will be able to connect to any of the three types. Searching for games will require less time and you minimize the chance of getting lags or kicks during a host rotation.
Choose your method.
On this guide I will show you, 2 methods in order to get an Open NAT type. The first method is easier,faster (takes just 2-3mins) but temporary. It's recommended for new players of osu! and generally speaking with people who don't have enough experience. The problem is that it's temporary. Everytime you restart your router or modem everything is reset. But as I stated above, even with that it will take you just 2-3 min. The second method requires a bit more experience but it's a peramanent solution to your problem. You have to edit your router's cfg file.
Before you choose your method.
TIP:At 80% you can skip the steps below except the UPNP and go directly to method A or B.

Before you choose your method, you have to forward the right ports. Don't worry, I will show you how. Let's start:
• Go start and type cmd then press enter.
• A window will pop up. Type on the command prompt (cmd) "ipconfig".
• Find the default gate address and write it down. In most cases it's 192.168.1.254
• Open your web browser and put the address which you have written down in the address tab.
• A window will pop up requesting your router's login info. Put your info there and your router's page will load up.
• Go to the port forwarding section of your router ( In Thomson routers it's the game and application sharing founded on the toolbox). Make sure to have enable your UPNP. Then you must forward the right ports (If you don't know how to port forward, you should download your router's manual or just visit the following site: http://portforward.com/ This site has also guides on how to port forward in your routers).
• The ports for TCP are 3074, 27014-27050 and for UDP are 3074 27000-27030.
• Apply your settings then reboot your router.


Method A
After you have rebooted your router / modem, you will follow theese instructions:
• Double click your icon "My computer". The window will pop up. At your left hand you will see an option called network. Click it.
• The page will load.
• Right click on Network Infrastructure and click properties.
• A window will pop up again. After that click Settings. You have to wait for a couple of seconds.
• A new window will appear. Click add at the bottom of the window.
• For one more time a new window will appear. Then do the following: in the first tab (name of service) put IW, in the second tab put your IPV4 address (To find it, go on cmd then type ipconfig.),
in the third tab put 28950 and don't forget to put UDP, and in the last tab you put again 28950. Then click ok.
• One more time click add. In the first tab you put osu! Bancho(or whatever you want I just prefer osu! Bancho), on the second tab you put your IPV4 address, in the third tab 3074 and don't forget to put UDP and in the last tab you put again 3074.
• You click ok, then again ok, then again ok.
• Launch osu!. Your NAT type should be opened.

Again I remind you that you have to do the procedure above every time you reboot your router or restarting every active connnections.

Method B
This is the method in which you will permamently fix the problem.
• Log in, on your router's page using one of the browsers.
• Go to your router's configuration page.
• Somewhere there must be an option called "Save or Restore Configuration". Click on it.
• A new page will load up. Use the option "back up configuration now.."
• Wait a couple of seconds and a window will pop up. Then click, save file, then ok.
• Make 2 copys of this file so if something's go wrong we will have a backup.
• Open the file.
• Hit down Ctrl + F and write [ connection.ini ]
• When you will find that, look for the last bind.
• Under the last bind paste this: "bind application=CONE(UDP) port=3074-3075" then under the last one paste this "bind application=CONE(UDP) port=3478-3479" then under the last one for one more time paste this "bind application=CONE(UDP) port=3658"
• After that save the file (Probably the file is opened with notebook.)
• Then go back to your router's page at the configuration tab where you have been before.
• Use the Option to browse your new configuration file.
• After that click "Restore Configuration Now". Be patient and wait.
• Close your router's page and reboot your router. When you launch Modern Warfarre 3 NAT should be Open.
Tips
•Method A works for Windows Vista (Service Pack 2), Windows 7, Windows 8 and 8.1, and Windows 10
•Method B works with the ones written above plus with the XP OS.
•If you finally didn't managed to open your NAT type, don't get angry or sad. Relax a bit and carefully follow step by step this guide. If you still have problems, feel free to add me and I will fix it for you.

Epilogue
This is my first guide so far. I tried to explain you with the simplest way I could, everything about NAT. Don't be angry or rude with me if I am wrong at some points. I will add soon videos and images for easier access. I would be greatfull to leave your comments so I would make the guide even better. Also if this guide worked for you, please Rate it and Favourite it. Thanks a lot!

A wide area network (WAN) is a telecommunications network or computer network that extends over a large geographical distance. Wide area networks are often established with leased telecommunication circuits.

Business, education and government entities use wide area networks to relay data to staff, students, clients, buyers, and suppliers from various locations across the world. In essence, this mode of telecommunication allows a business to effectively carry out its daily function regardless of location. The Internet may be considered a WAN.

Related terms for other types of networks are personal area networks (PANs), local area networks (LANs), campus area networks (CANs), or metropolitan area networks (MANs) which are usually limited to a room, building, campus or specific metropolitan area respectively.

Design options
The textbook definition of a WAN is a computer network spanning regions, countries, or even the world. However, in terms of the application of computer networking protocols and concepts, it may be best to view WANs as computer networking technologies used to transmit data over long distances, and between different LANs, MANs and other localised computer networking architectures. This distinction stems from the fact that common LAN technologies operating at lower layers of the OSI model (such as the forms of Ethernet or Wi-Fi) are often designed for physically proximal networks, and thus cannot transmit data over tens, hundreds or even thousands of miles or kilometres.

WANs do not just necessarily connect physically disparate LANs. A CAN, for example, may have a localized backbone of a WAN technology, which connects different LANs within a campus. This could be to facilitate higher bandwidth applications or provide better functionality for users in the CAN.

WANs are used to connect LANs and other types of networks together so that users and computers in one location can communicate with users and computers in other locations. Many WANs are built for one particular organization and are private. Others, built by Internet service providers, provide connections from an organization's LAN to the Internet. WANs are often built using leased lines. At each end of the leased line, a router connects the LAN on one side with a second router within the LAN on the other. Leased lines can be very expensive. Instead of using leased lines, WANs can also be built using less costly circuit switching or packet switching methods. Network protocols including TCP/IP deliver transport and addressing functions. Protocols including Packet over SONET/SDH, Multiprotocol Label Switching (MPLS), Asynchronous Transfer Mode (ATM) and Frame Relay are often used by service providers to deliver the links that are used in WANs. X.25 was an important early WAN protocol, and is often considered to be the "grandfather" of Frame Relay as many of the underlying protocols and functions of X.25 are still in use today (with upgrades) by Frame Relay.

Academic research into wide area networks can be broken down into three areas: mathematical models, network emulation and network simulation.

Performance improvements are sometimes delivered via wide area file services or WAN optimization.

Connection technology
Many technologies are available for wide area network links. Examples include circuit switched telephone lines, radio wave transmission, and optic fiber. New developments in technologies have successively increased transmission rates. In ca. 1960, a 110 bit/s (bits per second) line was normal on the edge of the WAN, while core links of 56 kbit/s to 64 kbit/s were considered fast. As of 2014, households are connected to the Internet with Dial-Up, ADSL, Cable, Wimax, 4G or fiber. The speeds that people can currently use range from 28.8 Kilobits per second through a 28K modem over a telephone connection to speeds as high as 100 Gigabits per second over an Ethernet 100GBaseY connection.

AT&T plans to start conducting trials in the year 2017 for businesses to use 400 Gigabit Ethernet. Researchers Robert Maher, Alex Alvarado, Domaniç Lavery & Polina Bayvel of University College London were able to increase networking speeds to 1.125 Terabits per second. Christos Santis, graduate student Scott Steger, Amnon Yariv, Martin and Eileen Summerfield developed a new laser that quadruples transfer speeds over fiber optic cabling. If these two technologies were combined, then a transfer speed of up to 4.5 Terabits per second could potentially be achieved, although it is unlikely that this will be commercially implemented in the near future.