Network conflict: Why does either Wi-Fi or wired internet work?

A situation where a computer loses visibility into the global network when a cable is connected, or, conversely, loses access to local resources when the wireless module is activated, is a classic sign of a network interface conflict. The operating system, accessing two active communication channels simultaneously, often fails to correctly determine the priority route for transmitting data packets. Instead of automatically switching to the faster wired Ethernet, the device may continue to attempt to send requests over an unstable Wi-Fi connection, or completely block the second interface due to IP address conflicts.

The root of the problem most often lies in incorrect operation DHCP servers, which assigns identical addresses to different devices, or incorrectly configured Windows routing tables. The user encounters paradoxical behavior: indicators show a connection, but browsers and applications fail to load any pages. Understanding how the operating system distributes traffic between physical and virtual adapters is the first step to troubleshooting without calling a technician.

In this article, we'll take a detailed look at the mechanics of these conflicts and offer step-by-step instructions for resolving them. We won't use complex terms without explanation, but rather focus on practical steps that will help you set up a stable network. A critical point is to check the uniqueness of IP addresses for each interface within the same subnet. If you encounter a similar problem, most likely it is enough to change the interface metric or reset the DNS cache.

Prioritize network connections in Windows

Windows operating systems use a special algorithm to determine which interface to send internet traffic through if multiple interfaces are enabled. By default, the system prefers a wired connection. Ethernet, as it is considered more stable and faster. However, this priority is not absolute and can be disrupted by software glitches or manual user settings previously made for other purposes.

Each network adapter is assigned a numerical value called a metric. The lower this number, the higher the interface's priority in the operating system's eyes. If the Wi-Fi and LAN card metrics are the same or are configured inconsistently, a situation arises where Windows It starts to "jump" between connections, leading to connection interruptions. It often happens that after updating drivers or the OS itself, the metric settings are reset to automatic, which triggers the conflict.

⚠️ Warning: Changing the network priority may temporarily disrupt access to local printers or network-attached storage (NAS) if they are tied to a specific IP address of the wireless adapter.

You can use the command line to check the current connection status and metrics. Enter the command route print and examine the list of interfaces. You need to find the line Active Routes and see which interface (specified by IP) is given preference for the default gateway address 0.0.0.0If you see different gateways specified for the same destinations, this is a clear sign of a problem.

IP address and subnet conflict

One of the most common reasons why the internet doesn't work when connected simultaneously is duplicate IP addresses. If your router distributes addresses in the range 192.168.1.x, and the corporate network or a second router you're connected to via Wi-Fi uses the same band, a conflict occurs. The computer doesn't know which device to send data packets to, and the network stack simply blocks one of the interfaces.

The solution lies in changing the address range of one of the devices. For example, if a home router uses a subnet 192.168.0.0/24, then the secondary connection must be in the range 192.168.1.0/24 or any other address that doesn't overlap with the first one. This is especially relevant for those using a "main router + repeater" combination or connecting to VPN servers with internal addresses that match their home address.

• 🔍 Check the default gateway IP address for your Wi-Fi adapter.
• 🔍 Compare it with the gateway IP address for the Ethernet adapter.
• 🔍 Make sure the first three digits of the address (e.g. 192.168.1) differ if the devices are on the same physical network.

If you cannot change the settings of the main router, try manually entering a static IP address for the problematic interface in the protocol settings. IPv4This will force the computer to ignore invalid DHCP server requests and use the settings you specified. However, be careful: an incorrectly specified gateway will completely disable internet access for that adapter.

Setting interface metrics manually

When automatic priority determination fails, manual interface metric configuration is the only reliable solution. This process requires accessing the network adapter properties via the control panel. No third-party software is required; all functionality is built into the standard interface. Windows 10 And Windows 11.

First, you need to open the network connections window. Press the key combination Win + R and enter the command ncpa.cplIn the window that opens, find your wireless adapter, right-click it, and select "Properties." Then find "Internet Protocol Version 4 (TCP/IPv4)" in the list, select it, and click "Properties" again.

In the lower right corner of the protocol properties window, click the "Advanced" button. Here you will see a checkbox next to "Automatically assign metric." This must be unchecked to activate the input field. Enter the value 10 for a priority connection (eg cable) and the value 20 or more for the secondary (Wi-Fi) channel. This will ensure the system uses the wired channel when available.

DNS and network cache issues

Sometimes the physical connection is established correctly, the metrics are configured correctly, but the internet still doesn't work when switching. In this case, the culprit is often DNS cache, which stores outdated routing records. The system attempts to use old access paths that are no longer relevant for the new connection type.

To clear the cache, you must run the command prompt as an administrator. This is a critical step, as the command will not run without administrator rights. Enter the command ipconfig /flushdns and press Enter. You should see a message indicating that the DNS cache has been successfully flushed. This action doesn't affect your personal files or passwords; it only clears temporary network tables.

It's also worth checking if you've hard-coded DNS server addresses that aren't available on your current network. For example, your cable provider's DNS might not work over a mobile phone's Wi-Fi hotspot. In your IPv4 settings, it's best to select "Obtain DNS server address automatically" unless you're using specific services like Google DNS or Cloudflare.

⚠️ Warning: If you are using a corporate network, changing DNS servers may block access to internal company resources. Please coordinate these changes with your system administrator.

Impact of drivers and virtual adapters

Modern computers are often equipped with multiple virtual network adapters created by virtualization software, VPN clients, or Android emulators. These virtual devices can take over control of real physical hardware, creating the illusion of network operation even though there's no actual network connection.

Outdated network card drivers are also a common cause of instability. Hardware manufacturers regularly release updates that fix interrupt handling issues and IRQ conflicts. If you have a driver that's several years old, it may simply not be able to properly handle new power saving standards or security protocols. WPA3.

netsh winsock reset
netsh int ip reset
ipconfig /release
ipconfig /renew