ThinkPad Ethernet Extension Adapter Gen 2 (PN: 4X90Q84427) not working with P15s Gen2

[Fostel]

Hi all,

I’ve been a user of this forum for years, though I haven’t been very active.
Firstly, I was not sure where to post this as I could not locate a P15 forum.

Recently, I purchased a used ThinkPad P15s Gen 2 (Model 20W6000PUK) with a broken USB-C port (the furthest one, which is the default charging port).

The second USB-C port (located next to the Lenovo proprietary port) is functional, so the laptop is still usable.

I intended to use a proprietary Lenovo Ethernet connection on the left side of this laptop.



Based on a Lenovo representative’s recommendation and the compatibility information listed here: [SMART Find Compatibility Info](https://smartfind.lenovo.com/accessorie ... 4X90Q84427), I purchased a genuine ThinkPad Ethernet Extension Adapter Gen 2 (P/N: 4X90Q84427)

The SMART Find website claims OS-independent compatibility with the ThinkPad P15 Series, including the P15s 2nd Generation (20W6, 20W7), and even PXE boot support.

Unfortunately, after extensive testing on both Windows and Linux, including adjustments to UEFI settings as per Lenovo's suggestions, the laptop does not recognize the adapter.
The same adapter works flawlessly with my ThinkPad T14 Gen 2, so the issue isn’t with the adapter itself.

Both machines are running the same version of Linux (Pop!_OS 22.04).

**My questions:**
- Is the proprietary port broken, or does this model simply not support the adapter?
- Could the Lenovo representative have been mistaken?
- Are there any specific UEFI settings I should try next?

Any advice would be greatly appreciated.

Thanks!

[RealBlackStuff]

P15 has now been added to the Forum title.

Why don't you use the regular ethernet port on the right-hand side instead?

[Fostel]

Workspace configuration forces me to rely on the left side for Ethernet, as the cable comes from that direction.

Since the main USB-C port is broken, I can only use the second, plastic one. I thought it would be a good idea to use the proprietary Ethernet port to avoid sacrificing another USB port.

However, Lenovo's design of the ThinkPad Ethernet Extension Adapter Gen 2 plug is problematic. It doesn’t fit properly if the adjacent USB-C port is in use, requiring modifications like trimming the plug with a Dremel. If the mod done nicely, the larger part of the Ethernet dongle would help mechanically support the USB-C connection.



Unfortunately, it seems this laptop doesn’t support Ethernet through the proprietary port, despite Lenovo’s claims on their website and assurances from their representative.

[RealBlackStuff]

You should either ask your work to get a longer cable, or get e.g. a short ethernet extension cable like this.

[dr_st]

Or a 40AH/40AJ docking station...

But if the port is damaged, the dock may not work either.

Isn't the machine under warranty?

[Fostel]

You should either ask your work to get a longer cable, or get e.g. a short ethernet extension cable like this.

Thank you for the suggestion, but that’s not the issue here.

I’m not struggling with the length of the LAN cable—it’s already long enough, and I am able to make my own cable if needed. However, this is my workspace, not a workplace, and its configuration is intentional: I want all cables connecting to the laptop from the left side to maintain a clean and efficient setup.

The main problem I’m highlighting is twofold:

1. The broken USB-C port limits my options, and I want to avoid sacrificing another USB port on this side unnecessarily.
2. The Lenovo proprietary Ethernet port, which I bought the official ThinkPad Ethernet Extension Adapter Gen 2 for, simply does not work with this laptop.

I’m not asking how to extend a cable—I’m asking whether this laptop model (P15s Gen 2) actually supports the Lenovo Ethernet adapter, despite Lenovo claiming compatibility on their website and through their representative.

The root of the issue is functionality, not cable length. I already have the adapter, and I want to use the ports on my laptop as I see fit. If this model doesn’t support the adapter, I’d like to understand why.

[Fostel]

Or a 40AH/40AJ docking station...
But if the port is damaged, the dock may not work either.
Isn't the machine under warranty?

Unfortunately, no—it’s just out of warranty by a few months. I got it for £175, so I figured it was a good enough deal to accept the issues.

Regarding the docks, I did consider this option, but if the proprietary Ethernet port is dead or not supported, I’m concerned it may not work with a dock either.

Also, does this model (P15s Gen 2) support both mechanical and USB-C docks, or is it Thunderbolt-only?

[RealBlackStuff]

See if this info helps.
Also, have you installed any necessary driver(s)?

Brand new BIOS here, try it.

[Fostel]

See if this info helps.
Also, have you installed any necessary driver(s)?

Brand new BIOS here, try it.

There is no driver for this dongle afaik. Not for linux I run this machine on.
Thanks for the tip about new bios. Installed but as expected this do not fix my issue here.