Fastest way with console:
1) Open a command window(Press ALT-F2 and type konsole if you use KDE and select Applications->Accessories->Terminal if you use GNOME)
2) Just copy and paste the following line into the console window
wget -O collectNWData.sh http://www.linux-tips-and-tricks.de/CND_download && chmod +x collectNWData.sh && ./collectNWData.sh

3) Check whether NWEliza found some configuration problems and follow the given hints to solve the problem on your own.

If no problems were reported by NWEliza then it's important to upload the contents of collectNWData.txt (You find it in the directory you downloaded the script into) to a nopaste service nopaste service and then post the link in your favorite Linux forum and provide valuable information about your network setup and configuration so the Linux community can quickly help you to solve your problem.

 

Alternate way with console:

1) Download script with your browser

2) Open a command window(Press ALT-F2 and type konsole if you use KDE and select Applications->Accessories->Terminal if you use GNOME)

  1. Type in console: cd ~/Downloads
  2. Type in console: bash ./collectNWData (ATTENTION! There is a leading period in front of  / !!!)
3) Check whether NWEliza found some configuration problems and follow the given hints to solve the problem on your own. If no problems were reported by NWEliza then it's important to upload the contents of collectNWData.txt (You find it in the directory you downloaded the script into) to a nopaste service and then post the link in your favorite Linux forum and provide valuable information about your network setup and configuration so the Linux community can quickly help you to solve your problem.
 
Everybody using Linux should be able to execute the script with the information given above. It's crucial to know how to use the console in Linux. There exists much more detailed information about the script.