The Gist#

I have ran into instances where I or my boots on the ground don’t have a console cable available for troubleshooting. So a hotspot needs to be fired up and they need to connect to the network with their interface. Whether that be the management interface on a UPS or one of those default networks on a firewall. (Yes, I keep those around for this scenario)

Windows has a tendancy of prioritizing the Ethernet adapter in the routing using a metric on the interface for IPv4 and IPv6. Which can be problematic when you’re in need of both wireless and Ethernet interfaces for troubleshooting.

The Troubleshooting Topology#

This little topology generally looks like this locally. Generally you have some RMM software your organization uses to manage the device remotely. But, without Internet connectivity. This isn’t possible in some cases.

Wireless Hot-Spot -> Computer Wifi -> Computer Ethernet -> Network to be Troubleshot

Getting The Interface Metric#

The following Cmdlet can be used to get the ifIndex, InterfaceAlias, and InterfaceMetric for the devices we’re looking for.

Get-NetIPInterface

Output below provides all of the information we need to set the configuration as needed. I’ll cover that in more detail in the next section.

ifIndex InterfaceAlias                  AddressFamily NlMtu(Bytes) InterfaceMetric Dhcp     ConnectionState PolicyStore
------- --------------                  ------------- ------------ --------------- ----     --------------- -----------
...
11      Ethernet                        IPv4                  1500               5 Enabled  Connected       ActiveStore
15      Wi-Fi                           IPv4                  1500              45 Enabled  Connected       ActiveStore
...

Updating The Interface Metric#

To update the metric we use the Set-NetIPInterface Cmdlet. Which can be used to update configuration for IP interfaces. This includes IPv6 discovery settings, router settings, DHCP, etc.

The objective here is to make the wireless interface the preferred route to the Internet because the Ethernet interface will not have Internet connectivity.

Windows routing will prefer the lower metric. So, we need to make the “InterfaceMetric” for Ethernet higher then Wi-Fi.

One way to think of this is to just get the sum of the Ethernet and Wi-Fi InterfaceMetric(s) and set that as the InterfaceMetric for the Etherent ifIndex. The value will be higher if that’s the case.

Set-NetIPInterface -InterfaceIndex <ifIndex> -InterfaceMetric <Metric higher then Ethernet>

This is how the command would look in this case.

Set-NetIPInterface -InterfaceIndex 11 -InterfaceMetric 50

Once we’re finished. We can verify our work. The InterfaceMetric for Ethernet is higher then the one for Wi-Fi.

ifIndex InterfaceAlias                  AddressFamily NlMtu(Bytes) InterfaceMetric Dhcp     ConnectionState PolicyStore
------- --------------                  ------------- ------------ --------------- ----     --------------- -----------
11      Ethernet                        IPv4                  1500              50 Enabled  Connected       ActiveStore
15      Wi-Fi                           IPv4                  1500              45 Enabled  Connected       ActiveStore

Verifying It Works#

For one you’ll be able to connect your RMM softwar to the computer. The user will have Internet connection from their computer. You’ll also be able to connect to the device you’re troubleshooting. Judging we’re discussing the same scenario.

Rolling Back#

One way to rollback this configuration is to set the InterfaceMetric back to he original value if a reboot doesn’t do the job. Not to mention if you would rather not reboot.

When setting it back consider subtracting the value of the Wi-Fi interface from the Ethernet interface and setting the Ethernet interface ifIndex InterfaceMetric to that value.

Or just set it to 5. I’ve seen that it usually defaults to 5.