Microsoft Network Connection Status - "No Internet Connection" but Can Get on Internet - Windows 10, 7

This has long been a random issue with all versions of Windows going back to at least Win 7, but we've been seeing it recently with Windows 10 as well.

Basically, when looking at the network status icon down by the clock, you will see a yellow triangle with an exclamation point in the middle.

When hovering your mouse over the icon, it will show the message "No Internet Available". Oddly enough, you can still browse the internet though you may find other things not working like Office 365 configured Outlook accounts, Windows updates, Steam, etc.

For Windows 10, this could be a bug within one of the releases affecting DHCP and normally a simple reboot will resolve the issue, at least temporarily. The first thing then to do is to check for any pending Windows updates and if any are available, install them to see if this resolves the issue.

If this fails, or you are unable to run updates, then for a more permanent workaround, we have been finding that disabling IPv4 checksum offload via Device Manager seems to have prevented this issue from recurring.

Disable IPv4 checksum offload

1. Click on the Windows start button, type out Device Manager, click on first result

2. Find the Network Adapter entry, expand the list, and right click on either your wired or wireless adapter and select "Properties"

3. Once the properties to the network adapter opens, select the "Advanced" tab, find and highlight the "IPv4 Checksum Offload" property, and change the value from "Rx & Tx Enabled" to "Disabled"

You will momentarily lose your internet connection but should it reconnect quickly. From here you should then find that the "No Internet" alert has gone away. 

The TCP offload engine is a function used by network cards to offload processing of the entire TCP/IP stack from the CPU to the network controller. By disabling it, you move processing back to the CPU. 

There are also some other steps you can try if you are worried about the CPU taking a hit with the extra load (which in our experience on Windows 10 machines has been negligible), but this workaround has consistently prevented this issue from returning.

NLA Service Startup

On slower networks, you may want to change the NLA (Network Location Awareness) service from "Automatic" to "Automatic (Delayed Start)". 

The Network Location Awareness service is a service that will dynamically adapt the firewall rules and security based on the network connection that you are on. It is what automatically detects and selects between Public, Private, and Domain networks. 

To change the service to a delayed start, do the following:

1. Launch services by clicking the Windows Start button, type "Services.msc" and hit "Enter"

2. Once Services opens, scroll down through the list and double click on "Network Location Awareness"

3. In the properties box that opens, from the Startup type drop down, change from "Automatic" to "Automatic (Delayed Start)", then hit "Apply" and "Ok"

Reset Winsock entries and TCP/IP stack

Launch a command prompt by clicking the Windows start button and typing "CMD", hit enter. Once the command prompt opens, run the following commands, one at a time(hit enter after each):

netsh winsock reset catalog

netsh int ipv4 resetlog.txt

netsh int ipv6 reset resetlog.txt

Once complete, reboot.