USB-C hubs feel simple—until they don’t. You plug a small adapter into your laptop at a desk or in a hotel room, HDMI lights up the monitor, your keyboard connects, and charging begins. Then, on a different laptop or display, something breaks: the screen stays black, two monitors mirror instead of extending, charging shows “slow,” or an external drive disconnects mid-transfer. If you’ve ever wondered why the same hub works perfectly in one setup but fails in another, you’re not alone. This guide turns common USB-C hub questions into practical, real-world checks—the same logic used when testing everyday hubs like Lemorele TC46 and TC100 across laptops, tablets, and handheld consoles—so you know what to check first, why it matters, and what your setup can realistically support.

1. Device Compatibility: What Works and What Doesn’t

1.1 What Devices Does a USB-C Hub Support?

A USB-C hub works with most devices that have a full-featured USB-C port, meaning the port supports DP Alt Mode (DisplayPort Alternate Mode).

In practical terms, DP Alt Mode allows a device to send a video signal through USB-C so the hub can output video over HDMI or DisplayPort.

Common compatible devices include:

• MacBook models with USB-C or Thunderbolt
• Many Windows laptops with USB-C video output
• iPad Pro and other USB-C iPads that support external displays
• Some Android phones that support USB-C video output (often tied to desktop-mode features)

A critical limitation to understand early:

A USB-C hub cannot add video output if your USB-C port does not support it.

If the port is data-only, HDMI on the hub will never work, regardless of cable or adapter.

1.1.1 Quick Check: Is Your USB-C Port Video-Capable?

In Lemorele user feedback, more than half of “HDMI black screen” cases are caused by USB-C ports that do not support video output—not by hub failure.

1.2 Can a USB-C Hub Work with a Desktop PC USB-C Port?

Often, no—even if the desktop includes a USB-C connector.

Many desktop motherboard USB-C ports are designed mainly for data transfer and may not provide:

• DP Alt Mode video output
• Power Delivery (PD) charging output

If DP Alt Mode is missing, the hub’s HDMI or VGA ports will not output video.

If PD output is missing, USB devices may still function, but charging and display features can fail or become unstable.

A practical rule:

If the motherboard documentation only lists USB speeds and does not mention DisplayPort or Thunderbolt, the port is likely data-only.

2. Video Output: 4K Support and Why Displays Sometimes Fail

2.1 Does a USB-C Hub Support 4K Video Output?

Yes, many USB-C hubs support 4K output, typically:

• 4K@30Hz on standard models TC100
• 4K@60Hz on higher-spec designs TC46

However, the hub’s specification is only one part of the equation. Actual resolution depends on:

• The host device’s USB-C video capability
• The monitor’s supported resolution and refresh rate
• The hub’s internal signal routing
• Whether one display or multiple displays are connected

A hub “supporting 4K” only means it is not the bottleneck. The system may still choose a lower mode for stability.

Why 4K Doesn’t Always Show Up (Even If the Hub Supports It)

A USB-C hub claiming 4K support does not guarantee the system will output 4K.

On full-featured hubs like TC46 or TC100, system policy often compromises before hardware limits are reached.

2.2 Why Is There No Image When I Connect HDMI?

A black screen is one of the most common complaints, and the cause is usually straightforward.

A USB-C hub’s HDMI output relies entirely on DP Alt Mode support from the host device.

Recommended troubleshooting steps:

• Confirm the hub is firmly connected to the USB-C port
• Switch the monitor to the correct HDMI input
• Test a different HDMI cable
• Try another USB-C port on the same device
• If still no image appears, DP Alt Mode is likely missing

When DP Alt Mode is absent, USB ports, SD cards, and Ethernet may still work, but video output will not.

2.3 Why Did HDMI Suddenly Lose Signal?

If HDMI worked previously and then suddenly shows “No Signal,” this is often caused by a temporary controller handshake issue rather than hardware failure.

Practical reset method:

• Unplug the hub from the device
• Shut down the laptop completely
• Press and hold the power button for about 40 seconds
• Power the laptop back on and reconnect the hub

This process clears residual charge and resets internal controller states.

2.4 How Do I Set Mirror Mode or Extend Mode?

Display layout is controlled by the operating system, not the hub.

On Windows:

• Press Windows + P
• Select Duplicate, Extend, or Second screen only

On macOS:

• Open System Settings
• Go to Displays
• Configure mirroring or extension if supported

The hub does not decide mirror or extend mode—the operating system does.

3. Multi-Monitor Limits: Why Resolution Drops or Displays Mirror

3.1 Why Can’t I Set Higher Resolution with Multiple HDMI Monitors?

When multiple displays share a single USB-C connection, display bandwidth is shared.

A common real-world outcome is dual displays running at 1080p@60Hz even though a single display can run at a higher resolution.

This usually means the system has lowered resolution to maintain stability.

3.2 Why Can’t My Hub Run Dual 4K@60Hz Correctly?

Running two 4K@60Hz displays simultaneously requires:

• A USB-C port capable of dual high-bandwidth video output
• Monitors that truly support 4K@60Hz
• A hub designed with sufficient internal bandwidth

If any condition fails, the system automatically falls back to a lower resolution or refresh rate.

3.3 Why Do Two Monitors Mirror on a MacBook?

This behavior comes from macOS not supporting standard MST expansion.

Seeing two HDMI ports does not guarantee dual extended displays on macOS.

3.4 What Display Modes Are Possible with Three Monitors?

When a hub connects two HDMI displays plus one VGA display, behavior depends on the operating system.

• On Windows, mixed mirrored and extended layouts may be available
• On macOS, one unique display with others mirrored is common

The key takeaway is that OS rules dominate multi-display behavior.

4. Power Delivery: Charging, Slow Charging, and Stability

4.1 Does the Hub Support Laptop PD Fast Charging?

Yes. Most USB-C hubs include a PD input port.

Typical behavior includes:

• Up to 100W PD input
• Around 85W maximum pass-through to the laptop

The difference exists because the hub itself consumes power for HDMI, USB, Ethernet, and internal controllers.

4.2 Why Doesn’t PD Charging Appear?

If the charger is connected but the laptop shows no charging:

• Confirm the charger is plugged into the PD input port
• Reseat the upstream USB-C cable
• Test a different PD charger
• Confirm the laptop’s USB-C port supports charging

Some ports support video but not charging, or the opposite.

4.3 Why Does the Laptop Show “Slow Charging”?

When HDMI, external storage, and Ethernet are active, the hub draws part of the available power.

In Lemorele testing, when PD power is insufficient, the system prefers reduced charging speed over unstable connections.

4.4 Can the PD Port Charge Other Devices Directly?

No. The PD port is designed as a power input for the hub, not as a standalone charger.

4.5 What Charger Should I Use?

The safest option is the laptop’s original USB-C charger.

If the laptop uses a barrel-type charger, confirm whether its USB-C port supports charging and at what wattage.

5. USB Ports, Storage, and Performance Expectations

5.1 Can I Use All Hub Ports at the Same Time?

In most cases, yes. However, stability depends on power and bandwidth.

A common scenario:

• The external monitor works normally
• Multiple external drives are connected
• One drive disconnects during a large file transfer

This is usually caused by power or bandwidth limits, not a defective hub.

5.2 Why Do External Drives Disconnect?

Most “disconnect during transfer” cases are power-related rather than speed-related.

5.3 Do SD and TF Card Slots Support Simultaneous Operation?

This depends on the hub’s internal controller design.

If simultaneous read/write matters, check the specific model’s specifications.

5.4 Why Isn’t 10Gbps Speed Reached?

Achieving 10Gbps requires:

• A host port that supports USB 3.1 Gen2 or higher
• Storage hardware capable of sustained high speed
• Proper cables and hub design

File size and caching behavior also affect real-world transfer speeds.

6. Audio: 3.5mm, HDMI Audio, and Limitations

6.1 Why Is There No Audio from the 3.5mm Port?

On many USB-C hubs, the 3.5mm jack follows HDMI audio routing.

Checklist:

• Confirm DP Alt Mode support
• Select HDMI or display audio in system sound settings
• Confirm the monitor supports HDMI audio

6.2 Can the 3.5mm Port Take Microphone Input?

No. The 3.5mm port is output-only.

6.3 Can I Use a USB-C Headset with the Hub?

Usually not. The USB-C port on a hub is intended for data devices, not USB-C audio output.

7. Ethernet: Drops, Speed, and Recovery

7.1 Why Does Ethernet Drop Intermittently?

Common causes include loose cables, IP conflicts, or outdated network drivers.

7.2 Why Isn’t Ethernet Detected When PD Is Connected?

Connect the PD charger and Ethernet cable first, then reseat the upstream USB-C cable to trigger re-enumeration.

7.3 Why Did Ethernet Suddenly Stop Working?

Simplify the setup:

• Disconnect all devices except Ethernet
• Reseat the upstream USB-C cable
• Reset network settings if needed

7.4 Why Isn’t 1Gbps Speed Reached?

To reach 1Gbps reliably, all components must support it.

A single weak link—cable, router port, or driver—will cap throughput.

8. Cables and Adapters: Hidden Compatibility Traps

8.1 Can I Use a USB-A Adapter with a USB-C Hub?

No for video output. USB-A cannot carry DP Alt Mode signals.

8.2 Can I Use a USB-C Extension Cable?

Not recommended. Extension cables often cause unstable negotiation, especially for video output.

9. Heat: What’s Normal?

USB-C hubs generate heat under load.

HDMI output, external storage, Ethernet, and PD all contribute to warmth.

Moderate heat is normal as long as performance remains stable.

10. Gaming Handhelds: Steam Deck and Switch Tips

10.1 Can I Use the Hub with Steam Deck or Switch?

Yes, but setup expectations differ.

• Steam Deck generally supports docked use smoothly
• Nintendo Switch requires sufficient external power

10.2 Why Does Switch Need a 45W Adapter for HDMI?

Without enough power headroom, HDMI output will not activate.

A 45W or higher adapter, or the official Nintendo power supply, is required for stable docked output.