C6300 Modem/Router connection problems

I fought this problem for months and finally discovered that the problem for me was the PSP (Power Save Polling) feature of my Windows laptop, which is not supported by this router. In short, when the laptop's wifi adapter would "sleep" in power saving mode, it would basically block all connections to the router, and I would lose all connections (phones etc.) on the 2.5G channel that the laptop was using. To fix this, go to your Device Manager, click on Network Adapters, right click on wireless adapter (or ethernet adapter if wired), click properties, click Power Management, and UNselect "Allow the computer to turn off this device to save power". Mine has worked flawlessly ever since doing this. Hope this helps.