Whats wrong with my Internet! YouTube lags a lot ?

Its probably because there's more than one person/device connected to the router. If that's so, then make sure that one device is connected to the router, remember once at a time for each device. BECAUSE if every device more than 3 devices are connected to the router than you will experience problems. ALSO, there is something called an extension for the router which increases the Radius which covers the area your in so that you can get perfect connection.

Do you use any VoIP services like Vonage, NetTalk, Magic Jack, ect? Those can eat up bandwidth by connecting and disconnecting themselves to the Internet, in the background. This can cause the WiFi access to lag. How many devices do you have connected to your high-speed access? Your devices could also be to blame, because they can only handle so much speed before the processor becomes overloaded. Do you have a mobile phone that you could connect to your WiFi and then use apps on the phone to test your data connection?

Do you use any VoIP services like Vonage, NetTalk, Magic Jack, ect? Those can eat up bandwidth by connecting and disconnecting themselves to the Internet, in the background. This can cause the WiFi access to lag. How many devices do you have connected to your high-speed access? Your devices could also be to blame, because they can only handle so much speed before the processor becomes overloaded. Do you have a mobile phone that you could connect to your WiFi and then use apps on the phone to test your data connection?