If you experience issues such as unrecognized devices or certain USB peripherals (e.g., keyboards or mice) not functioning when a secondary USB hub is connected to the docking station, this behavior is usually caused by USB hierarchy limitations defined by the USB specification.

According to USB protocol standards (including USB 2.0 and USB 3.0), a USB device chain supports a maximum depth of five hub levels. This means data can pass through up to five hubs between the host computer and the end device, forming a total of six tiers, with the host computer counted as Tier 0.

In typical laptop setups, the USB signal path already includes internal hubs. To provide multiple suitable USB ports, the host system must first split the USB signal through an internal hub. As a result, devices connected directly to a laptop are often already operating at Tier 1 or Tier 2 in the USB hierarchy.

When a docking station is connected, it introduces additional hub levels into the signal chain. Connecting a second external USB hub to the docking station can further extend the chain and may push it beyond the supported USB hierarchy depth.

When this limit is exceeded, some downstream devices may not be recognized, or only certain ports may function properly.

For clarity, USB hierarchy levels are defined as follows:

Tier 1 Hub: Directly connected to the host computer.

Tier 2 Hub: Connected to a downstream port of a Tier 1 hub.

Tier 3 Hub: Connected to a downstream port of a Tier 2 hub.

Tier 4 Hub: Connected to a downstream port of a Tier 3 hub.

Tier 5 Hub: Connected to a downstream port of a Tier 4 hub.

Devices connected beyond Tier 5 may fail to operate correctly.

On Anker Prime TB5 Docking Station, not all USB ports share the same internal hierarchy level. Because hubs with four or more ports often include multiple internal hub layers, port hierarchy depends on the product's internal design. On this model, the rear USB-A ports operate at a higher hierarchy level than the front USB-A ports.

If connecting a second hub or KVM device to a rear USB-A port causes the device to malfunction, we recommend trying one of the front USB-A ports, which operate at a lower hierarchy level and may resolve the issue.

If you have any questions, please contact Anker Customer Support for further assistance.