I was supplied a Cisco DPC3825 modem by my ISP and use a Cisco E4200 as my main router.

Today the Internet just stopped working, just out of the blue, I can't think of anything that would have triggered it. It's been working pretty good for the past month except for a few random blips here and there.

After some trouble shooting I realized that a direct wired connection to the modem would get me Internet access but if I was wired to the router as I was before I would have no connection. Assuming it was router I connected a TP-Link WR841N but it had the exact same problem. Also, connecting to the router via Wi-Fi from multiple devices will connect me to the router but I still can't get access to the Internet. From these test, it seems that the modem just won't send Internet through to the router but is clearly connecting and able to directly connect to my PC.

What I've Tried

• A full reset and factory reset on the E4200
• A full reset on the modem (but I believe my ISP has remote access to the modem because the passwords and so on are always set back).
• My ISP has remotely reconfigured the modem

What I Should Try
What else can I try? What should I do to try to narrow down the issue? Can you figure out what the problem might be based on this information?