MacBook Air M1 Docking Station issue

Looking at the iTec site (I-Tec – Products), I see that several of their docks are listed as "USB 3.0 / USB-C" docks, by which they seem to mean "USB-A / USB-C". USB-A is not designed to support video signals, so when you see USB-A docks that let you attach displays, this is a sign that some sort of "stunt box" workaround is involved.

Take, for instance, the. i-tec USB 3.0 / USB-C / Thunderbolt Dual Display Docking Station + Power Delivery 100W

They call it a "Thunderbolt" docking station, but there is no indication that it actually is one. The description talks of it being "Thunderbolt-compatible"; at one point, they also mention USB4. But I believe what they really mean is that if you plug it into a Thunderbolt port or a USB4 port it will work using the USB 3.* support is typically present on any Thunderbolt 3, Thunderbolt 4, or USB4 port.

The data sheet says that it "features the DisplayLink DL3900 chipset and offers the flexibility of both USB-C and USB-A host interfaces" and says that the "docking station technology" is "DisplayLink + USB-C PD".

In other words, it sounds like this thing doesn't even try to take advantage of USB-C (DisplayPort Alt Mode). It just uses the DisplayLink "stunt box" workaround for both of its displays, all of the time. If you plugged it into a M1 MacBook Air on which you had not installed DisplayLink drivers, you would not get a picture on any display plugged into this particular dock, as the dock would be ignoring the M1 MacBook Air's native DisplayPort output.

Your docking station could well be the issue.

If this is a dock that uses some workaround like DisplayLink to drive its monitor outputs, none of the display outputs that depend on the workaround will provide a signal unless you are running special matching driver software on the computer attached to the dock. Neither the "stunt box" alone nor the drivers alone will get you a signal. You must use them as a pair.

thedecmyster wrote:

Thanks for this info I didn't take what you mentioned into consideration, Just can't get my head around how both displays will work with my PC connected too the Dock via USB-C. I can get one of the Monitors too work by connecting it too my MacBook directly using a HDMI too USB-C Adaptor anyway.

Your symptoms are consistent with a dock that has only "stunt box" outputs, combined with a PC that has the "stunt box" drivers installed, and a Mac that doesn't. I don't know which specific iTec dock you have, but that "USB 3.0 / USB-C / Thunderbolt" dock sure seemed to be a low-end "stunt box".

The only reason that that "both displays … work with [your] PC" might be that, at some time in the past, you or someone else installed DisplayLink drivers on that PC.

"Stunt box" workarounds do not work unless there is a special chip set in the adapter or dock, and a matching driver installed on the computer using it. If either is missing or not installed, you will get no signal. When both things are present, you may get a signal. Even then, this will not be as good as a connection that relies on your computer's first-class hardware-supported video output.

Synaptics is the company that provides DisplayLink chip sets, and matching drivers. If the particular dock that you're using is DisplayLink-based, you might find Mac drivers and troubleshooting articles here:

Synaptics – DisplayLink