I have Dell Vostro running Windows 10 Insider build. Now the problem is that my internet automatically start showing yellow no connectivity icon. I disconnect it and again connect and it start working. It happen automatically in very short interval of time.
Try Control Panel -> Troubleshooter -> Network Adapter, when it goes wrong, Then try Internet Connection and so on, try to determine, where the problem is.
Also you could try opening a command prompt (CMD) and type ipconfig, to determine your IP address (when the system is functioning), then when it fails try to ping'ing your router's IP address, if this works, it is DNS.