I'm using a recently purchased Windows 11 computer over Ethernet. The connection worked normally for several weeks, but it began showing "Connected, no Internet." After reinstalling the motherboard's network drivers and disconnecting the cable, it temporarily recovered. Now the computer falls back to Wi‑Fi whenever it starts, and Ethernet still does not work properly.
Windows' troubleshooter has reported several different issues, including being unable to reach the default gateway, a DNS cache problem, and poor network quality. However, I can ping the gateway, ping both IP addresses and hostnames, use nslookup, and run ping and tracert successfully. Applications that need an Internet connection still fail when Ethernet is active.
I have removed my VPN, disabled proxies, disabled network-adapter power saving, reinstalled the latest drivers, flushed DNS, released and renewed the address, reset Winsock, restarted the computer repeatedly, and tested in Safe Mode. I also tried different Ethernet cables, router or switch ports, and manual DNS servers such as 8.8.8.8 and 8.8.4.4. The same cables and ports work correctly for another computer, while Wi‑Fi works but is extremely slow. What else could be causing Ethernet traffic from applications to fail even though basic network tests succeed?
3 Answers
A switch can cause strange intermittent behavior even when ping appears to work. If the Ethernet cable passes through a separate switch, bypass it and connect the computer directly to the router or gateway. Also test the computer on a completely different network if possible. That will help distinguish a bad switch or router negotiation issue from a faulty adapter in the computer.
Successful ping and DNS lookups do not prove that normal application traffic is working. Check for security software, firewall rules, leftover VPN filter drivers, or a broken proxy configuration. In Windows, verify that no proxy is enabled under the system network settings, temporarily test with third-party security software disabled, and inspect the adapter’s installed network components for old VPN or filtering drivers. If Ethernet has a different profile than Wi‑Fi, remove the Ethernet network profile and reconnect so Windows recreates it.
Since another computer works with the same cable and ports, the cable and router connection are less likely to be the problem. That points toward the Ethernet adapter, its driver, or software filtering traffic on this particular PC. Check whether the adapter is negotiating at the expected speed, and try completely removing the adapter and its driver from Device Manager before installing a clean driver package. If the problem persists with a clean Windows installation or a different USB-to-Ethernet adapter, the onboard network hardware may be failing.
Safe Mode usually rules out many startup applications, but some filter drivers can still remain active. A clean boot or temporarily uninstalling every VPN and network-filtering component is more useful than only disabling the VPN application.