Lenovo USB-C to Ethernet Adapter
PRODUCT DESCRIPTION
Lenovo USB-C to Ethernet Adapter (4X90S91831) - Local Warranty
Gigabit Ethernet From a Laptop That Has None
The Lenovo USB-C to Ethernet Adapter gives a USB-C laptop a gigabit RJ45 network port. Lenovo publishes conformance with IEEE 802.3ab for gigabit and IEEE 802.3 for 100 Mbps. It draws its power from the USB-C port and needs no external supply.
It Does PXE Boot and Wake-on-LAN, Which Is the Point
Lenovo's own description is that it is "ideal for imaging of systems or transferring large files quickly". That is not marketing filler: the adapter supports PXE boot and Wake-on-LAN on compatible systems, and MAC address pass-through on select ThinkPads. For an IT team that images machines over the network, an adapter without those features is useless and one with them is essential.
Wired Beats Wi-Fi for Two Jobs
Imaging a machine, and moving a very large file. Both are cases where a wired gigabit connection is not merely faster but more reliable — a dropped Wi-Fi association halfway through an OS deployment is a real problem. At 44 grams packed, this is the smallest way to have that capability in a bag.
Two Honest Notes
First, Lenovo's US storefront marks this part number End Of Life, while it remains listed as available on Lenovo Malaysia and other Asia-Pacific stores. Second, Lenovo publishes no warranty term, no dimensions and no cable length for it, and we could find no specification document on a Lenovo-owned domain — the figures above come from a Lenovo-authored datasheet that we could only reach through a distributor's mirror.
Lenovo USB-C to Ethernet Adapter Datasheet — Technical Specifications
General
| Product | Lenovo USB-C to Ethernet Adapter |
| Part Number | 4X90S91831 |
| Type | USB-C to gigabit Ethernet network adapter |
| Manufacturer Warranty | Not published by Lenovo for this part number |
| Local Warranty (Singapore) | Included with every SourceIT purchase, with GST invoice |
Lifecycle
| Status | Lenovo's US storefront marks this part number End Of Life, while Lenovo Malaysia and other Asia-Pacific storefronts still list it as available |
| Before You Order | Ask us to confirm current stock, particularly for quantity or for a standard you intend to keep |
Function
| Converts | USB-C (male, to the laptop) to RJ45 Ethernet (female) |
| Ethernet Speed | Gigabit. Lenovo states conformance with IEEE 802.3ab for gigabit and IEEE 802.3 for 100 Mbps |
| External Power | Not required — bus powered from the USB-C port |
Management Features
| PXE Boot | Supported on compatible systems |
| Wake-on-LAN | Supported on compatible systems |
| MAC Address Pass-Through | Supported on select ThinkPad models. Lenovo does not publish the list — ask us and we will check your machines |
Physical
| Weight | 44 g packed |
| Dimensions | Not published by Lenovo for this part number |
| Cable Length | Not published by Lenovo for this part number |
| Colour | Not published by Lenovo for this part number |
Documentation
| Lenovo-Hosted Specification | We could not find one. The IEEE conformance, PXE, Wake-on-LAN, MAC pass-through and 44 g figures above come from a Lenovo-authored datasheet that we could only reach through a distributor's mirror rather than a lenovo.com URL |
| A Document That Does Not Apply | Lenovo's support article acc100324 covers the older 4X90L66917 USB-C to Ethernet Adapter, not this part number. If you find it while researching, it is the wrong product |
| Warranty | Not published by Lenovo for this part number in any source we could reach |
Compatibility & Fit
Who actually needs this. IT teams imaging machines over the network; anyone moving multi-gigabyte files where a Wi-Fi drop would mean starting again; people working in venues with unreliable or captive-portal Wi-Fi; and any site where policy requires a wired connection for certain work. For ordinary browsing and email, the laptop's Wi-Fi is fine and this adapter is unnecessary.
PXE boot is the specification that separates a real adapter from a cheap one. It lets a machine boot from the network with nothing on its disk — the standard way an IT team deploys or rebuilds a laptop. Plenty of generic USB Ethernet adapters cannot do it. Lenovo publishes support for it here, along with Wake-on-LAN and, on select ThinkPads, MAC address pass-through so a docked machine keeps a consistent network identity.
If you also need video and USB ports, buy a hub instead. The Powered USB-C Travel Hub and the USB-C Travel Hub Gen 2 in the ordering table both include gigabit Ethernet alongside HDMI, VGA and USB-A. This adapter is the right buy when Ethernet is the only thing missing.
Being straight about our sourcing. We could not find a specification document for this adapter on a Lenovo-owned web address. The figures on this page come from a Lenovo-authored datasheet reached through a distributor's mirror, which is a notch weaker than our usual standard, and we would rather tell you that than present it as a Lenovo-hosted source. Lenovo publishes no warranty term, no dimensions and no cable length for the product at all. Ask us and we will get what you need confirmed with the distributor.
Package Contents & Lenovo Accessory Ordering Information
In the box, per Lenovo PSREF:
- Lenovo USB-C to Ethernet Adapter
- Publications
Lenovo Cables, Adapters and Security Ordering Information
| 4X90S92381 | Lenovo Powered USB-C Travel Hub — HDMI 4K60, VGA, GbE, 2 x USB-A, 52 W pass-through |
| 4X91A30366 | Lenovo USB-C Travel Hub Gen 2 — HDMI, VGA, GbE, USB-A — no power pass-through |
| 4X90V55523 | Lenovo USB-C 7-in-1 Hub — HDMI, 3 x USB-A, SD and microSD, charging — no Ethernet |
| 4X90S91831 (this listing) | Lenovo USB-C to Ethernet Adapter — Gigabit Ethernet from a USB-C port, PXE boot and Wake-on-LAN |
| 0B47069 | Lenovo HDMI to VGA Monitor Adapter — HDMI to VGA at 1080p60, 20 cm — video only, no audio |
| 4X20M26276 | Lenovo 65W Standard AC Adapter USB Type-C — 65 W USB-C PD 3.0 replacement charger, UK plug |
| 40AW0065WW | Lenovo 65W USB-C AC Travel Adapter — 65 W with four interchangeable plugs and a pouch |
| 4XE1F30276 | Lenovo NanoSaver Essential Cable Lock — Keyed, 2 keys, 1.5 m x 4.5 mm — Nano slot only |
| 4XE1F30277 | Lenovo NanoSaver Combination Cable Lock — 4-dial combination, 1.8 m x 5 mm — Nano slot only |
Datasheet & Downloads
We could not locate a specification document for this adapter on a Lenovo-owned domain. The technical figures on this page come from a Lenovo-authored datasheet that circulates through distributor mirrors, and we are flagging that rather than presenting it as a Lenovo-hosted source. Note also that Lenovo's support article acc100324 covers the older 4X90L66917 adapter, not this part number.
Frequently Asked Questions — Lenovo USB-C to Ethernet Adapter
Does it support PXE boot?
Yes, along with Wake-on-LAN, on compatible systems — and MAC address pass-through on select ThinkPads. That is the main reason to buy a manufacturer's adapter rather than a generic one: many cheap USB Ethernet adapters cannot boot a machine from the network.
Does it need its own power supply?
No. It is bus powered from the laptop's USB-C port.
Is it discontinued?
Lenovo's US storefront marks it End Of Life, while Lenovo Malaysia and other Asia-Pacific storefronts still list it as available — a mixed signal rather than a clear one. Ask us to confirm stock before you order, especially in quantity.
What warranty applies in Singapore?
Lenovo publishes no warranty term for this part number in any source we could reach, so this page does not state one. Every unit SourceIT sells carries local Singapore warranty support and a GST invoice, and we will confirm Lenovo's manufacturer term for you before you order.
How long is the cable?
Lenovo does not publish it, nor the adapter's dimensions. The only physical figure Lenovo gives is a 44 g packed weight. Ask us and we will measure one for you.
