关于USB-C扩展坞与单向USB-C线缆兼容性及长距离双向USB-C线缆推荐的技术咨询

Hi there, let's walk through your questions clearly to help you get this sorted:

First, let's clarify the unidirectional USB-C optical cable confusion #

That "computer" vs "display" marking on the cable isn't just about power passivity—it does mean the cable only works one way for signal transmission, and this is a dealbreaker for your docking station setup.

Here's why: Unidirectional USB-C optical cables are designed exclusively for video output scenarios. They only carry video signals from the "computer" end to the "display" end. The fiber inside doesn't support the two-way communication your ICY-BOX docking station needs:

• Your setup requires the host PC to send video signals to the docking station's monitors, and the docking station to send USB data back to the PC (like input from a keyboard/mouse, or file transfers from a USB drive plugged into the dock).
• Unidirectional cables lack the bidirectional data channels needed for USB communication—some even only route the video-related pins of the USB-C connector, completely ignoring the USB data pins. So your dock either won't be recognized by the PC, or any USB devices connected to it won't work at all.

Recommendations for a 20m (or 15m) bidirectional USB-C cable #

For long distances (10m+), regular copper USB-C cables suffer too much signal loss, so you need an active optical USB-C cable (AOC) that's explicitly marked as bidirectional and full-featured. Here's what to look for:

• Must-have features:
  • Explicitly labeled "bi-directional" or "full-function USB-C"
  • Supports USB 3.2 Gen 2 (or higher) for reliable USB data transfer
  • Supports DisplayPort Alt Mode (critical for driving your two monitors from the dock)
  • Supports Power Delivery (PD) so your dock can draw power from the PC if needed
• Reliable brand options:
  • StarTech offers a 20m USB-C 3.2 Gen 2 Active Optical Cable that checks all these boxes—fully bidirectional, supports video and USB data.
  • Belkin's USB-C Active Optical Cable (20m version) is another solid pick, built for long-distance full-function USB-C use.
  • If 20m is hard to source, 15m versions from these brands are more widely available, with the same bidirectional, full-featured support.

Just double-check the product specs before buying to make sure it explicitly mentions bidirectional transmission and support for both video (DisplayPort Alt Mode) and USB data—don't settle for a cable only marketed for video output.

备注：内容来源于stack exchange，提问作者Håkon Seljåsen