ASUS · ExpertBook B1 B1502 · i5-1235U
Ethernet Not Working Fix
Ethernet not working on the ASUS ExpertBook B1 B1502 means the RJ-45 port does not establish a network connection, Device Manager shows an error on the Realtek Ethernet controller, or Windows reports the cable is unplugged even with a cable connected. Follow the steps below in order.
Fix 1: Update Realtek Ethernet Driver from ASUS
Download the Realtek LAN driver for the ExpertBook B1502 from ASUS Support. In Device Manager, uninstall the current Realtek PCIe Family Controller entry (check the driver deletion box) and restart. Run the ASUS Realtek LAN installer. The ASUS-certified Realtek LAN driver includes B1502-specific NIC initialization settings not in the generic Realtek driver package.
Fix 2: Disable Realtek Ethernet Power Management
Open Device Manager → Network Adapters → Realtek PCIe Family Controller → Properties → Power Management. Uncheck Allow the computer to turn off this device to save power. Also in the Advanced tab, find Energy Efficient Ethernet (EEE) and set it to Disabled. EEE can cause the Realtek NIC to drop the Ethernet link when traffic is light, which appears as Ethernet disconnecting randomly after a few minutes of idle time. The ExpertBook B1502 Realtek NIC is particularly sensitive to EEE-related link drops on certain managed switches.
Fix 3: Check ASUS BIOS LAN Controller Setting
Restart and press F2 for ASUS BIOS. Navigate to Advanced → Onboard Devices Configuration and confirm Realtek LAN Controller is Enabled. If the LAN controller is disabled in BIOS, the Realtek adapter will not appear in Device Manager at all and Ethernet will not function regardless of driver state. Enterprise ExpertBook B1502 units configured for Wi-Fi-only deployment may have the LAN controller disabled in BIOS by the deploying organization.
Per Syafiq Azhari, IT administrator deploying ASUS ExpertBook B1502 units in an office: “Several B1502 units arrived with LAN disabled in BIOS from the factory configuration. Ethernet was not working despite correct drivers. Enabling LAN Controller in ASUS BIOS Onboard Devices fixed it for all affected units immediately.”
Frequently Asked Questions
Why is Ethernet not working on ASUS ExpertBook B1 B1502?
The Realtek LAN driver needs updating, the LAN controller is disabled in BIOS, or Energy Efficient Ethernet is causing link drops. Install the Realtek LAN driver from ASUS Support for the B1502, enable LAN in BIOS Onboard Devices, and disable EEE in the Realtek driver Advanced settings.
Does ASUS ExpertBook B1 B1502 have a built-in Ethernet port?
Yes. The B1502 includes a Realtek PCIe Gigabit Ethernet port (RJ-45, 1Gbps). This is a dedicated physical port on the chassis, not a USB adapter. It supports standard Cat5e and Cat6 Ethernet cables. The LAN port is separate from the Wi-Fi 6 adapter (Intel AX201).
Why does Ethernet show unidentified network on ExpertBook B1502?
The IP address configuration is incorrect or the DHCP server is not assigning an address. Open Network and Sharing Center, click the Ethernet adapter, and select Properties. Confirm IPv4 is set to Obtain an address automatically. If DHCP is correct, release and renew the IP address by running ipconfig /release and ipconfig /renew in an elevated CMD.
Can I use a USB-C to Ethernet adapter on ASUS ExpertBook B1502?
Yes. The B1502 has a USB-C port. Connect a USB-C to RJ-45 Ethernet adapter and Windows will install a generic or manufacturer-supplied USB Ethernet driver automatically. The USB-C Ethernet adapter works in addition to or instead of the built-in Realtek Gigabit port. For reliable Gigabit Ethernet performance, the built-in Realtek port is preferred over USB adapters due to lower latency and no USB overhead.
Conclusion
Ethernet not working on the ASUS ExpertBook B1 B1502 i5-1235U is fixed by updating the Realtek LAN driver from ASUS Support, verifying the LAN controller is enabled in BIOS Onboard Devices, and disabling Energy Efficient Ethernet in the Realtek driver Advanced properties. Uncheck power management for the Realtek NIC in Device Manager to prevent idle-based Ethernet link drops. Test with a known-good Ethernet cable and check the RJ-45 link LEDs to confirm physical cable connectivity before troubleshooting drivers.
Ryan holds a Computer Science degree and has over 20 years of hands-on experience with PC hardware, software, and driver troubleshooting. He is the author behind softwaredriverdownload.com, where he helps everyday users fix driver issues quickly and accurately. Ryan has personally tested most of the fixes on this site across a range of Windows 10 and Windows 11 machines.
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