My Windows PC has a Realtek Gaming 2.5GbE Family Controller. Ethernet shows as connected and negotiates at 1 Gbps, but DHCP fails and Windows assigns a 169.254.x.x address instead of an address on my network's 192.168.68.x range. Wi-Fi works normally, and the router's gateway is 192.168.68.1.
I have already tried resetting Winsock and TCP/IP, releasing and renewing the address, restarting the adapter, rebooting the PC, changing Speed & Duplex back to Auto Negotiation, disabling Priority and VLAN, checking the adapter properties, and completely power-cycling the computer. DHCP was enabled during the original failure; it was only disabled temporarily while testing a static configuration.
I also tested a static configuration using 192.168.68.200/24 with gateway 192.168.68.1, but Ethernet still could not reliably ping the router or reach the internet. With Wi-Fi disabled, even pinging 192.168.68.1 can return "PING: transmit failed. General failure." Returning to automatic addressing immediately produces another 169.254.x.x address.
I have tried multiple cables and different router connections, including a direct connection rather than going through the mesh setup. The same network connection works on another computer. Could this be a corrupted Realtek driver, a damaged Ethernet adapter, a binding or advanced-property problem, or something else? What would you check before replacing the adapter?
4 Answers
The gateway is not something DHCP needs to be manually entered to find. DHCP supplies the address, subnet mask, gateway, and DNS settings after the client reaches the DHCP server. Manually entering a gateway while DHCP is failing will not fix the underlying communication problem. Also, 255.255.0.0 was likely part of the temporary or automatic configuration; the expected mask for a 192.168.68.x home network is commonly 255.255.255.0, but the router’s actual settings should be confirmed.
A 169.254.x.x address means Windows gave up waiting for DHCP; it does not indicate a usable connection. A negotiated 1 Gbps link only proves that the physical layer detected a signal. It does not prove that Ethernet frames are successfully reaching the router.
For testing, leave Speed & Duplex on Auto Negotiation, connect directly to the router, try another router LAN port, and verify the cable. Also test another device on that exact port and cable. If another computer works there, the PC’s adapter, driver, or Windows networking configuration becomes the likely culprit.
The next practical test would be a USB-to-Ethernet adapter. It bypasses the built-in Realtek controller and its driver. If the USB adapter gets a 192.168.68.x address immediately, the onboard adapter or its driver is probably faulty. If it also fails, then investigate Windows bindings, security software, or the router’s access-control settings instead.
A clean driver reinstall is reasonable, but remove the existing device and driver package through Device Manager first, reboot, and install the current driver from the PC or motherboard manufacturer. Before reinstalling, check that IPv4 is enabled on the adapter and that the normal Client for Microsoft Networks and IPv4 bindings are present. Leave checksum offloads, jumbo frames, VLAN options, and other advanced settings at their defaults while testing.
I tested multiple cables and direct router connections, and the same setup works on my brother’s PC, so the problem appears specific to this computer.