realtek pcie gbe family controller driver - RTL8139

Realtek RTL8139 Driver, Ethernet Missing, No Internet, Code 10, Windows 10/11 Setup, PCI Fast Ethernet, and LAN Detection Problems

The Realtek RTL8139 is a 10/100 Fast Ethernet network adapter used in older desktop PCs, PCI LAN cards, and legacy motherboard LAN setups. It provides wired Ethernet access, so it is usually the device users need working first after a clean Windows install when the computer has no internet connection. 

Users most commonly faced missing Ethernet after reinstalling Windows, driver install loops, Code 10 or unknown-device states, no internet despite a detected adapter, old RTL8139/810x driver confusion, and Windows 10 or Windows 11 compatibility uncertainty.

Problem: Realtek RTL8139 missing after Windows reinstall

What users observed: After reinstalling Windows, users found that the computer had no wired internet connection. Device Manager could show an unknown Ethernet Controller, a missing Network adapters section, or no usable Realtek RTL8139 entry. This usually happened on older desktop systems where Windows did not attach the LAN driver automatically.

What was tried: Users checked Device Manager, tried Windows automatic driver search, installed Realtek LAN packages, restarted Windows, and tested the Ethernet cable/router with another device.

How this played out: The repair path was manual LAN driver installation. Users downloaded the Realtek RTL8139 or RTL8139/810x Fast Ethernet driver on another computer, moved it by USB, installed it on the offline PC, restarted, and checked whether the adapter appeared under Network adapters. Once Ethernet worked, the rest of the missing drivers could be installed from the same system.

Problem: Realtek RTL8139 appears as Ethernet Controller under Other devices

What users observed: Users saw a yellow warning icon under Other devices instead of a proper Realtek network adapter. Windows knew a network controller existed, but it did not have the right driver attached.

What was tried: Users opened Device Manager, checked hardware IDs, tried automatic driver search, selected Browse my computer, used Let me pick from a list, and tested Realtek driver packages.

How this played out: The fix was to attach the Realtek driver manually. Users selected the correct Realtek RTL8139/810x or RTL8139 Family Fast Ethernet driver package, installed it through Device Manager, and restarted Windows. When the correct driver attached, the device moved from Other devices to Network adapters.

Problem: Realtek RTL8139 driver installs but Ethernet still has no internet

What users observed: Users installed the driver and saw the Realtek adapter appear, but the network still did not work. Windows could show the adapter as enabled, yet there was no internet access, no IP address, or limited connectivity.

What was tried: Users changed Ethernet cables, tested another router port, checked IP settings, restarted the router, disabled and re-enabled the adapter, and reinstalled the driver.

How this played out: The repair path moved beyond the driver. Users confirmed the link light, tested a different cable and router port, checked whether Windows received an IP address, reset the adapter, and verified that DHCP was working. Once the adapter was installed correctly, no-internet cases moved to cable, router, IP configuration, or adapter hardware condition.

Problem: Realtek RTL8139 shows Code 10 or device cannot start

What users observed: Some users saw the RTL8139 listed in Device Manager but with a Code 10 or cannot-start state. The adapter was detected, but Windows could not start the device normally.

What was tried: Users uninstalled the device, restarted Windows, reinstalled the Realtek driver, tried an older driver package, moved the PCI card to another slot, and tested the card in another computer.

How this played out: The fix path was driver-version and hardware-slot testing. Users removed the failed device entry, installed a driver version that matched the RTL8139/810x family, and reseated the PCI card where applicable. If the card still failed in another PC, the adapter itself became the likely failure point rather than Windows.

Problem: Realtek RTL8139 is not detected at all

What users observed: In some cases, the RTL8139 did not appear in Device Manager, even as an unknown Ethernet controller. On PCI card systems, there might be no network adapter entry at all.

What was tried: Users checked BIOS onboard LAN settings where relevant, reseated the PCI card, tried another PCI slot, checked whether the card appeared in another PC, and looked for physical link lights.

How this played out: The repair moved to hardware detection. Users confirmed that onboard LAN was enabled in BIOS if the RTL8139 was built into the motherboard, or reseated the PCI card if it was an add-in adapter. If Windows and BIOS never saw the device, and the card also failed in another system, reinstalling the driver did not solve the issue. One driver listing notes that many newer operating systems have built-in support for this device family, so a completely undetected card can point to hardware or slot failure rather than only a missing driver.

Problem: Realtek RTL8139 Ethernet link says cable unplugged

What users observed: Windows showed the Realtek adapter, but the network status said the cable was unplugged. The cable was connected, but Windows did not detect a live Ethernet link.

What was tried: Users changed Ethernet cables, tried another router or switch port, checked link lights, disabled and re-enabled the adapter, changed speed/duplex settings, and restarted Windows.

How this played out: The repair path was physical-link validation. Users tested a known-good cable and router port first. If link lights returned, the adapter was working. If the RTL8139 still showed unplugged across multiple cables and ports, users tested another PCI slot or another adapter. Driver reinstalling did not fix a dead physical link.

Problem: Realtek RTL8139 connects only at 10 Mbps or has unstable speed

What users observed: Users saw the connection work but at a very low speed, or the connection dropped during use. Since RTL8139 is a 10/100 Fast Ethernet device, it will never behave like a Gigabit adapter, but it should still negotiate a stable 100 Mbps link when the cable and switch allow it.

What was tried: Users checked adapter speed, replaced cables, changed switch/router ports, adjusted speed and duplex, and tested another network card.

How this played out: The fix was speed/duplex and cable correction. Users set auto-negotiation first, tested a better cable, changed router/switch ports, and only forced 100 Mbps full duplex when auto-negotiation failed. If the adapter stayed unstable across several cables and ports, the old card or motherboard LAN hardware became the focus.

Problem: Realtek RTL8139 works after restart but disappears later

What users observed: Users reported that the adapter worked after reboot or reinstall, then later disappeared, disabled itself, or stopped passing traffic. This behavior looked like a driver problem but could also involve old PCI hardware, power management, or Windows update replacing the driver.

What was tried: Users disabled power saving, reinstalled the driver, rolled back a driver update, checked Device Manager after each reboot, and tested the card in another slot.

How this played out: The repair path was driver persistence and power-state cleanup. Users disabled power management for the adapter, prevented Windows from switching to a bad driver where rollback helped, and reseated the PCI card. 

Problem: Realtek RTL8139 stops working after Windows update

What users observed: After a Windows update, users could lose wired network access even though the adapter had worked before. The adapter might remain visible but fail to connect, or the driver version might change.

What was tried: Users checked Device Manager, rolled back the driver, uninstalled the adapter, restarted Windows, installed the Realtek package again, and checked IP/network status.

How this played out: The fix was to restore the working driver state. Users rolled back the adapter driver when the previous version worked, or removed the updated driver and reinstalled the known Realtek RTL8139 package.

Problem: Realtek RTL8139 is installed but there is no Network Connections entry

What users observed: Users saw the driver package installed or partially installed, but the adapter did not appear as a usable connection under Windows network settings. This happened in broader Realtek Ethernet cases after clean installs where the driver did not bind properly to the device.

What was tried: Users opened Device Manager, checked Network adapters, checked Other devices, manually selected a driver from a list, and restarted Windows.

How this played out: The fix was driver binding through Device Manager. Users manually selected the Realtek Ethernet driver for the detected controller, restarted Windows, and checked whether the adapter created a normal network connection. Installing a package alone was not enough if Windows did not bind it to the device.

Problem: Realtek RTL8139 appears in BIOS or PCI list but LAN port does not work

What users observed: Some users saw the RTL8139 card identified by hardware ID or BIOS-level listing, but the LAN port did not function in Windows. One reported case involved the NIC showing a Realtek-style identifier while the port still did not work normally.

What was tried: Users checked BIOS settings, installed a compatible RTL8139 driver, uninstalled older drivers, restarted, and tested the LAN port again.

How this played out: The repair path was to combine BIOS/device recognition with the correct Windows driver. Users confirmed the card was not disabled, removed stale drivers, installed the matching RTL8139 driver, and tested the port with a known-good cable. If BIOS detected the card but Windows never brought up a live link, users tested the card in another slot or another PC.