I'm troubleshooting a Windows PC whose Realtek Gaming 2.5GbE Family Controller shows as connected and negotiates at 1 Gbps, but Ethernet never receives a normal IPv4 address. Wi-Fi works correctly on the same network. The router uses the 192.168.68.x network, with 192.168.68.1 as the gateway. Ethernet initially fell back to 169.254.17.201 with no usable default gateway, and ipconfig /renew reported that the DHCP request timed out. DHCP was enabled when the problem first occurred.
I reset the network stack with ipconfig, netsh winsock reset, and netsh int ip reset, restarted the PC, toggled the adapter, restored Speed & Duplex to Auto Negotiation, and tested various Realtek options including Priority/VLAN, checksum offloads, jumbo frames, and flow control. The adapter reports Status Up and LinkSpeed 1 Gbps.
I also temporarily assigned 192.168.68.200/24 with gateway 192.168.68.1 and public DNS servers. Windows accepted the configuration, but with Wi-Fi disabled I still could not ping the gateway or the internet. Pinging the gateway sometimes returned "Transmit failed. General failure." Removing the static settings caused Ethernet to return to a 169.254.x.x address. DHCP has since been re-enabled and DNS reset to automatic.
The PC has been fully powered down and disconnected from power, and I have tried multiple Ethernet cables and connecting directly to the main router instead of the mesh equipment. Another computer works through the same network connection. Could this be a damaged adapter, driver or binding problem, or a hardware issue that still allows link negotiation but prevents actual traffic? What should I test next?
4 Answers
A clean driver reinstall is worth trying, but remove the device completely through Device Manager first and select the option to remove the driver package if Windows offers it. Then install a current driver from the computer or motherboard manufacturer, rather than relying only on the existing Windows driver. Also check the adapter’s IPv4 properties and make sure they are set to obtain both the IP address and DNS automatically.
A 169.254.x.x address means Windows gave up waiting for DHCP; it does not indicate a working connection. A negotiated 1 Gbps link only proves that the Ethernet hardware detects a signal. It does not prove that packets can pass. Keep Speed & Duplex on Auto Negotiation, connect directly to the router, try another router port, and confirm that the port is a normal LAN port rather than a tagged or specially configured VLAN port.
The 255.255.0.0 mask seen with 169.254.x.x is normal for Windows automatic private addressing and is not the cause. DHCP does not require you to manually enter a gateway. If a static 192.168.68.200 address still cannot ping 192.168.68.1, the failure is below DNS and usually points to the cable, switch/router port, VLAN configuration, driver, adapter, or broken network bindings.
Test the network path with another device using the exact same router port and cable. If that device works, the problem is probably local to the PC or its Ethernet adapter. Since another computer works and you have already tried different cables and direct router connections, a USB Ethernet adapter is a useful next test. If the USB adapter gets DHCP immediately, the onboard Realtek adapter or its driver is likely faulty.
I tested multiple cables, changed ports, and connected directly to the main router. Another computer works on the network, so I’m also starting to suspect the onboard adapter or its driver.