New Router/Modem. Wireless works Lan goes on/off

I have Time Warner Cable and Live in the Southern California Area where they have just upgraded to fiber optic speeds for free. With new speeds came a new router/modem combo. My Internet via Ethernet cable worked perfectly fine until the new modem/router was installed with new speeds. Wireless works all the time with no issues. My LAN however is intermittent. Via windows 8 it never says I am disconnected form the internet but web pages won't load (this happens at random times, every 20-30 mins or so). If i have lets say a skype call going and I am browsing the web, my skype call would still continue without interruption and but my web pages won't load at random times. So I'll get web browsing for approx 30 mins or so and go without it for about 2-3 minutes and most programs/games requiring internet access does not work during the downtime.

I am no networking genius so i'd appreciate if you can explain any possible solutions as if it was for dummies.

What I've tried-
Modem/Router Hard reset.
New Ethernet Cables
DNS changes on primary secondary and tertiary ip addresses

Modem/Router Combo-
Arris DG1670A

Computer-
I5 Ivy Bridge 3570k
MSI Z77a-G41 MOBO
Corsair Vengeance 1x8gb 1600 Ram
Antec EA750 powersupply
R9 290X Video Card