USB4NET or USB4 Interdomain connections not working on Z890 platform (USB4 or TB4 host to host connection)

Question

USB4NET or USB4 Interdomain connections not working on Z890 platform (USB4 or TB4 host to host connection)

ron fucci 26

I have Z890 motherboards from various manufacturers.

I tried to establish a direct connection from one USB4 (or TB4) port on one host to another host.

Once the TB4 cable is plugged in there is no recognition of the other host device on either the TB control panel or on the USB4 host devices page in settings. At least on the ASUS platform once can choose the behavior i.e. as USB4 or TB4.

Why is this simple 'Thunderbolt Networking' not working? or what is the secret to get it to work?

This is easy on the Z690 platform. Just plug two hosts together with a TB4 cable using the built in TB4 ports and it WORKS.

HELP.

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Answer accepted by question author

KAMRAN ALI 240

Hi @ron fucci ,

The reason this isn't showing up in the Intel Thunderbolt Control Center is that Z890 uses the native Windows 11 USB4 driver stack instead of the legacy Intel driver software used on Z690. Because of this architectural shift, the old control panel won't detect or manage native USB4 connections.

Here is how to get the direct host-to-host connection working on Z890:

Check BIOS Settings: Go to your BIOS USB4/Thunderbolt settings on both boards. Make sure PCIe Tunneling is Enabled, and if your ASUS board gives you the option, set the port mode explicitly to Thunderbolt 4 instead of standard USB4.
Look in Device Manager (Ignore the TB App): Connect the TB4 cable between both PCs and open Device Manager > Network adapters. You should see a Microsoft USB4 Net Adapter or Thunderbolt Ethernet Adapter pop up automatically.
Assign Static IPs: Direct host-to-host connections don't have a DHCP router to assign IP addresses. Open the properties of the USB4/Thunderbolt network adapter on both PCs and configure static IPv4 addresses on the same subnet (e.g., 192.168.50.1 on PC 1 and 192.168.50.2 on PC 2, with subnet mask 255.255.255.0).
Try Intel Thunderbolt Share: For modern Core Ultra / Z890 platforms, Intel also offers the Thunderbolt Share app, which handles PC-to-PC file transfer and networking over TB4/TB5 cables without needing manual IP setup.

Let me know if the network adapter shows up in Device Manager once connected!

If this helps solve the problem, please click "Yes" and upvote the response.

ron fucci 26 Reputation points

2026-08-31T19:43:54.4833333+00:00

@kamran well done!

This also proves the natural superiority of human intellect to truly 'artificial' intelligence. (AI provided an overly complicated answer w/o really answering the question directly as you did)

Another item you might want to add to this list is to open the Network Connections and you will see an additional icon pop up to represent the host-host connection with an APIPA address.

For interested readers on Thunderbolt Networking, the white paper circa 2014 can be downloaded from Microsoft called "Thunderbolt™ Networking Bridging and Routing Instructional White Paper"
ron fucci 26 Reputation points

2026-09-04T18:02:19.94+00:00

Kamran

I was able to see the network connection established using USB4 and the 2 different hosts with APIPA addresses with a new P2P network adapter on each board - these adapters can ping each other directly (no need for static IP for this test)

I am using two different Gigabyte Z890 boards to run some TB4/USB4 tests.

The newest bios for each GB model does not agree with the USB4 options shown in the z890 BIOS guide. For instance, per the bios documentation there should be visible in the bios of each board, several options to control TB4 and USB4. None of these options are visible in the current bios (e.g. no option to control PCIE tunneling of USB4)

On an ASUS Z890 board bios I can see an option for 'firmware CM' which I believe uses the thunderbolt 4 controller vs the same controller embedded in USB4.

Do you know of a reference guide that provides guidance on how to use the TB4 controller directly and bypass USB4?

Thanks

RF

1 additional answer

Your answer

ron fucci 26 Reputation points

2026-08-31T19:43:54.4833333+00:00

@kamran well done!

This also proves the natural superiority of human intellect to truly 'artificial' intelligence. (AI provided an overly complicated answer w/o really answering the question directly as you did)

Another item you might want to add to this list is to open the Network Connections and you will see an additional icon pop up to represent the host-host connection with an APIPA address.

For interested readers on Thunderbolt Networking, the white paper circa 2014 can be downloaded from Microsoft called "Thunderbolt™ Networking Bridging and Routing Instructional White Paper"
ron fucci 26 Reputation points

2026-09-04T18:02:19.94+00:00

Kamran

I was able to see the network connection established using USB4 and the 2 different hosts with APIPA addresses with a new P2P network adapter on each board - these adapters can ping each other directly (no need for static IP for this test)

I am using two different Gigabyte Z890 boards to run some TB4/USB4 tests.

The newest bios for each GB model does not agree with the USB4 options shown in the z890 BIOS guide. For instance, per the bios documentation there should be visible in the bios of each board, several options to control TB4 and USB4. None of these options are visible in the current bios (e.g. no option to control PCIE tunneling of USB4)

On an ASUS Z890 board bios I can see an option for 'firmware CM' which I believe uses the thunderbolt 4 controller vs the same controller embedded in USB4.

Do you know of a reference guide that provides guidance on how to use the TB4 controller directly and bypass USB4?

Thanks

RF

Answer 1

For Windows USB4 host-to-host networking to work, the connection must enumerate as an Ethernet over USB4 interdomain connection, also called USB4NET. On supported systems, Windows creates a new network adapter and automatically assigns a link-local IPv4 address in 169.254.0.0/16. File sharing then works by browsing to \\<peer IP address>.

What to check on the Z890 systems:

Use a direct host-to-host connection between two PCs Windows only treats connections between two separate PCs as functional interdomain connections. Loopback-style connections on the same system are ignored.
Confirm Windows created the USB4 P2P network adapter After connecting the two PCs with a USB4 or Thunderbolt 3/4 compatible cable, a new network adapter should appear. If no adapter appears, Windows has not established the interdomain network tunnel.
Check the adapter IP addresses Open the network adapter properties on both systems and verify each side received a 169.254.x.x address.
Test basic connectivity Try to ping the peer IP address. If ping fails, make sure firewall settings allow it. Windows documentation states network discovery must be enabled, or the network type changed to Private, where network discovery is on by default.
Verify file sharing settings Ensure firewall and network sharing settings allow file sharing. Turn on Public folder sharing on the PC being accessed, then test with \\<peer IP> in Windows Explorer.
Do not rely on USB4 Settings or Thunderbolt UI to prove host-to-host networking The documented Windows behavior for USB4 interdomain is the appearance of a virtual network adapter (USB4P2PNetAdapter.sys), not necessarily peer visibility in the USB4 Hubs and Devices page or Thunderbolt control UI.
Check whether interdomain support is being blocked Windows supports disabling USB4 interdomain functionality by blocking the compatible ID USB4\USB4NET through device installation policy. If that policy is present, the USB4 P2P network adapter will not start. The corresponding MDM policy name is DeviceInstallation/PreventInstallationOfMatchingDeviceIDs.
Check for USB4 router problems in Device Manager USB4 required testing states the USB4 host and device routers should not be in a failed Plug and Play state and should not show a yellow bang in Device Manager.

Important platform requirement:

Windows requires the OS-provided USB4 connection manager starting with Windows 11.
At the firmware/BIOS level, interdomain USB4 connections must always be enabled. If USB tunneling, DisplayPort tunneling, or interdomain connections are disabled, the connection manager places the device into a failed state.

Based on the documented behavior, the “secret” is not a Thunderbolt control-panel action. The expected success path is:

connect the two PCs with a USB4-capable connection,
confirm a USB4 P2P network adapter appears,
confirm both sides get 169.254.x.x addresses,
then access the peer by IP address.

If none of the Z890 systems ever enumerate the USB4 P2P network adapter, the likely issue is that the platform firmware or policy is not exposing/enabling Windows interdomain support correctly rather than a file-sharing configuration issue.