You have several tools to configure the network on Centos 7.

• nmtui (From the package NetworkManager-tui)
• mmcli (From the package NetworkManager)
• nm-connection-editor (If you have a GUI running Gnome Desktop Environment)

Please take note that in Centos 7 the default network service is managed by the NetworkManager which is a dynamic network control and configuration daemon.

To scan all Wifi networks try using the command sudo iwlist scan

wlan0    unassociated  Nickname:"rtl_wifi"
         Mode:Managed  Access Point: Not-Associated   Sensitivity:0/0
         Retry:off   RTS thr:off   Fragment thr:off
         Power Management:off
         Link Quality:0  Signal level:0  Noise level:0
         Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
         Tx excessive retries:0  Invalid misc:0   Missed beacon:0

You can connect to your WPA2 access point by putting the following in /etc/network/interfaces

auto wlan0
iface wlan0 inet dhcp
wpa-ssid <your_router>
wpa-psk <your_wpa_key>

Get the system to read and use the changes:

sudo ifdown wlan0 && sudo ifup -v wlan0

FIRST STEP

To fix the WIFI problem, you need to change the power management settings for wifi network adapeter

• Go to Control Panel > Device Manager 
• Under "Network Adapters" right click and open the properties for your wireless adapter 
• Under the "power management" tab, uncheck " Allow the computer to turn off this device to save power" 

Reboot! 

If it continues to do not work, try this

SECOND STEP

Change your DNS, view this video guide.

Suppose you have successfull setup up your local webserver Tomcat or a simple Node.js HTTP server available locally through http://localhost:8080 and now you need to access Raspberry Pi from outside from LAN, then you are in the right place! This easy tutorial is for you.

The WiFi Router of your LAN has an external IP address which it uses to communicate with the internet, let's take a look at how to find. You can obtain the IP by querying Google with this url

https://www.google.com/search?q=my+ip


The result should be something like 80.76.56.11

Now get the local LAN IP address assigned to your Raspberry Pi by typing this command in the terminal window:

ifconfig

On the resulting text, you find the IP address after "inet addr:" for example 192.168.1.6

Configure the WiFi Router

• connect using browser to http://192.168.1.1/ (the default address of your router) and then log in by using your router's user name and password. 

• search "Port Forwarding" section (Port Forwarding is the ability to open ports in your router and re-direct data through those ports to a single PC on your network)  

• give a name to the new rule (webserver). Type the Raspberry Pi LAN ip address. Choose the protocol as TCP. Type in external port 80 (the port number available for Internet connections) and internal 8080 (the port number for your webserver on the Raspberry Pi). Click on Add or Apply to save the rule. 

Test the configuration by opening a browser from your PC o your smartphone and going to your public IP.

http://YourPublicIpAddress in this tutorial example for me is http://80.76.56.11

If all is well, you should see the html hosted on your local Raspberry Pi appear in your browser.