# USB‑C device‑mode network expansion card (USB Ethernet)

**URL:** <https://community.frame.work/t/usb-c-device-mode-network-expansion-card-usb-ethernet/82754>\
**Category:** Expansion Card\
**Created:** [May 26, 2026, 11:29pm UTC](https://community.frame.work/t/usb-c-device-mode-network-expansion-card-usb-ethernet/82754 "2026-05-26T23:29:35Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![violet697](https://avatars.discourse-cdn.com/v4/letter/v/b77776/32.png) [@violet697](https://community.frame.work/u/violet697)\
**Post date:** [May 26, 2026, 11:29pm UTC](https://community.frame.work/t/usb-c-device-mode-network-expansion-card-usb-ethernet/82754/1 "2026-05-26T23:29:35Z")

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New thin laptops often drop the RJ45, and it’d be really handy to get a low‑latency wired link between two laptops (for LAN gaming, fast file transfers, etc.). What if we made a USB‑C expansion card that can act like phones do — present itself as a network device over USB (USB‑Ethernet) when you connect two machines with a Type‑C cable?

I know it’s a niche use case, but seems neat. I might be missing something or be off-base — is this a sensible idea? Would love feedback.

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**Author:** ![Conor](https://sea1.discourse-cdn.com/flex001/user_avatar/community.frame.work/conor/32/29835_2.png) [@Conor](https://community.frame.work/u/Conor)\
**Post date:** [May 27, 2026, 1:19am UTC](https://community.frame.work/t/usb-c-device-mode-network-expansion-card-usb-ethernet/82754/2 "2026-05-27T01:19:22Z")

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The USB4 spec supports interdomain connection (i.e. you can achieve laptop-to-laptop networking over USB-C). Certain ports wired to certain Framework Laptop mainboards support USB4 (a couple of examples: FW13 AMD Ryzen AI 300 ports [Expansion Card Functionality on Framework Laptop 13 (AMD Ryzen™ AI 300 Series)](https://knowledgebase.frame.work/expansion-card-functionality-on-framework-laptop-13-amd-ryzen-ai-300-series-Hy5SfMRs1l) , FW16 AMD Ryzen 7040 ports [Expansion Card Slot functionality on Framework Laptop 16 (AMD Ryzen™ 7040 Series)](https://knowledgebase.frame.work/expansion-card-slot-functionality-on-framework-laptop-16-amd-ryzen-7040-series-rkUjGm7cn)).

Microsoft’s published info on USB4 interdomain connections: [Universal Serial Bus 4 (USB4&trade;) interdomain connections | Microsoft Learn](https://learn.microsoft.com/en-us/windows-hardware/design/component-guidelines/usb4-interdomain-connections)

This also remains true for USB-C ports that are rated Thunderbolt 3 or higher.

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**Author:** ![violet697](https://avatars.discourse-cdn.com/v4/letter/v/b77776/32.png) [@violet697](https://community.frame.work/u/violet697)\
**Post date:** [May 27, 2026, 1:38am UTC](https://community.frame.work/t/usb-c-device-mode-network-expansion-card-usb-ethernet/82754/3 "2026-05-27T01:38:03Z")

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Thanks for the explanation. I suspected this already existed but couldn’t find clear info.

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**Author:** ![Neo\_Huyghe](https://sea1.discourse-cdn.com/flex001/user_avatar/community.frame.work/neo_huyghe/32/47931_2.png) [@Neo\_Huyghe](https://community.frame.work/u/Neo_Huyghe)\
**Post date:** [May 28, 2026, 10:46am UTC](https://community.frame.work/t/usb-c-device-mode-network-expansion-card-usb-ethernet/82754/4 "2026-05-28T10:46:31Z")

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you need something named USB Gadget Mode