These are my thoughts after a few months use. I’ve split the review into DisplayLink and ALogic DX3 sections. Most of my complaints are about DisplayLink and I think would be the same no matter which dock/USB adapter you choose.

Alogic DX3

• The DX3 has 3 DisplayPort ports, but only two of them are DisplayLink compatible. The third one uses Alternate Mode (I think?) over USB-C to pass the DisplayPort signal directly to the monitor. This was good for me as I could make my center display DisplayPort and use DisplayLink on the peripheral display.
• The dock comes with a hefty external power supply almost the size and weight of the dock. The dock has a power button on the front which I thought was unnecessary at first but came in handy as I often need to restart the dock for the Mac to detect one or both of the displays. I’ve had this issue on a 2019 Intel Macbook Pro with directly connected DisplayPort cables so I suspect this may be more of a macOS problem. Having the power button on the front is much more convenient than unplugging the displays or turning the displays off and on.
• I haven’t had any issues with the USB ports. I haven’t pushed them very hard, but I also haven’t noticed anything “wonky” about them either. I have a 10-port USB hub that I plug into the dock and it seems to work fine including for an audio interface.

DisplayLink

• With a 4K display, macOS will let you choose a higher resolution to render at, which it will then downscale to the 4K pixels that are actually on the display. When I first bought the DX3, DisplayLink version 1.4 wouldn’t allow you to do this, the maximum resolution you could pick was 1920x1080 points at 2k (native 4K resolution). When writing this article, I went back to the feature request and found that they had released version 1.5 which was meant to fix this issue. It lets you choose 2560x1440 points but also renders at 2560x1440 pixels, instead of 5120x2880 pixels, downscaled to 4K. The good news is that it looks like they are continuing to work on the software and addressing limitations so hopefully this will be fixed in a future update.
• DisplayLink 1.4 was doing something which prevented you from using Apple Watch to unlock your computer. I discovered that it also stopped you from using your Watch as an admin password. However, the 1.5 update has a checkbox to “Use Apple Watch to unlock on login screen”. When you check that, the Watch unlock appears to work at the login screen and in everywhere else Watch unlock would work. I’m not sure why that wouldn’t just be a default setting?
• Note that you can’t evaluate DisplayLink CPU usage just by looking at the “DisplayLinkUserAgent” process. You also need to look at the WindowServer process, as DisplayLink causes work to be done there when rendering to the virtual display.
• The DisplayLink software could do with more diagnostics on what is happening. Currently you can’t see which displays are controlled by DisplayLink and which are directly connected.
• The DisplayLink software doesn’t seem to have any way to automatically update or even notify you of updates so you’ll need to check the website yourself.
• I haven’t noticed any latency from the compression/decompression signal transfer, but I’m only using the displays for writing code and web browsing so I wouldn’t expect many problems.

Other

• I’ve had a weird bug where sometimes the MacBook display won’t turn on for 10-60 seconds after opening the laptop, even when I’ve been using it only a few minutes prior. I’m not sure if this is related to DisplayLink software or just a macOS bug.

Summary

Overall, the ALogic DX3 dock serves it’s purpose well. If you had any other option, I wouldn’t recommend choosing DisplayLink technology, but with an M1 Mac this your best (and only) option. However, I’m encouraged that DisplayLink are continuing to improve the Mac user experience. When I upgrade to a new MacBook Pro, I’ll either use the DX3 without DisplayLink (if that will work), or sell it and purchase a standard Thunderbolt 4 dock.

I needed to buy a new Mac recently. I couldn’t bring myself to buy a legacy Intel Mac, but the new M1 Macs only support up to two displays. For the MacBook Air, MacBook Pro, and iMac that means you can connect one additional display along with the built-in display. For the Mac Mini, you can add two displays. I wanted a MacBook Air and already had two external displays which I wanted to keep using.

Update: I ended up purchasing the ALogic DX3 and wrote a follow-up post about my experiences with it.

DisplayLink

What are your options if you want to run more than two displays? Enter DisplayLink. DisplayLink (not to be confused with DisplayPort) is the name of a technology created by a company also named DisplayLink. It lets you send a video signal to a display over USB or Wi-Fi instead of via DisplayPort or HDMI. DisplayLink technology was first used in laptop docking stations but can now be found in other video-related products including adapter cables and monitors.

DisplayLink has two components - a software driver installed on your computer and a hardware chip in the dock or adapter. The software driver presents itself as one or more displays to the computer. The computer sends pixel data to the software driver, which then compresses the data and sends it over USB. The DisplayLink chip decompresses the data and sends the display signal to the (real) display.

I was pleasantly surprised to see that DisplayLink’s drivers have been updated for Apple Silicon and don’t require a kernel extension. From what I can tell, DisplayLink seems to be publishing regular updates to their drivers and is actively working on new features.

DisplayLink Limitations

Sending compressed video over USB is a pretty neat trick! However, DisplayLink has quite a few downsides to be aware of.

An uncompressed 4K60 video signal requires 12 Gbps of bandwidth. The latest DisplayLink chips run over USB 3.0 which has a bandwidth of 5 Gbps. Even a single 4K signal is too big, let alone multiple displays. This is why DisplayLink needs to compress the captured screen.

For desktop browsing, email, software development, and other general computer tasks where the display doesn’t change much from frame to frame, DisplayLink compression can be very efficient and is unlikely to be noticeable. DisplayLink claims “Pixel-perfect graphics”, and “Compression tuned for video content and high-quality graphics” on their newer chipsets. If you’re a video/photo/graphics professional, you’d probably want to check and see if this works for you.

It doesn’t sound like it will be as good for gaming though:

While DisplayLink technology is targeted primarily to productivity and video applications, it is suitable for the casual gamer. If you’re a “power gamer”, looking for every edge possible over your opponents, you might want to go another route.

Another downside to DisplayLink is that you need to install an optional program to show the Lock Screen on a DisplayLink monitor. Otherwise, the Lock Screen will only show up on the built-in display.

Unlock with Apple Watch doesn’t work when using DisplayLink. Apple disables Unlock with Apple Watch with the message “Unlocking with Apple Watch is not available while your screen is being shared”.

DisplayLink has a few other limitations on Macs: HDCP is not supported so you may not be able to watch Netflix, Hulu, iTunes Movies, etc.; only 4 external displays are supported; screen rotation is not supported; Clamshell mode is partially supported. Manufacturers publish blog posts announcing that new DisplayLink drivers are validated with their hardware, it’s probably good to check with your manufacturer before updating.

There are quite a few limitations to using DisplayLink to extend your displays. However, it’s also currently the only way to run more than two displays on a Mac, so if you need that then you’ll need to look at a DisplayLink powered Dock.

Choosing a Dock

If you already have a dock without DisplayLink, your cheapest option may be to purchase a DisplayLink USB adapter. You could connect your monitor to the adapter, and then the adapter to a free USB port. DisplayLink keeps a list of USB adapters you can purchase. Check compatibility as not all adapters list support for macOS, although sometimes the reviews will mention that they do still work.

DisplayLink sells chipsets to dock manufacturers. The chipset has their DisplayLink hardware, along with other ports like USB, Ethernet, Audio. This means that products from different manufacturers like Targus, Dell, Alogic, Plugable, Kensington can end up with very similar capabilities because they are all using the same electronics.

Unfortunately, all of the M1 compatible docks I saw had a maximum of one USB-C port. If you have a lot of USB-C devices you’ll either need to purchase USB-A->USB-C adapters or buy a non-DisplayLink dock and a DisplayLink adapter.

If you’re investigating docks, you may see reference to USB-C Alternate Mode. This is a way for a USB-C port to run non-USB signals over it like DisplayPort and Thunderbolt(!). Alternate Mode doesn’t let you run any more displays than you could otherwise do natively.

Dock Options

If you’re looking for a list of DisplayLink docks, DisplayLink has a list of DisplayLink docks. Here’s a list of docks that the manufacturers have said are supported on M1 Macs as a starting point:

Plugable has a few options:

• UD-3900PDZ, $160 - 3 HDMI ports, 1 supports 4K30, the other 2 only support 1080p/60Hz. 60W Power Delivery, 6 USB-A 3.0 ports, 3.5mm audio jack.
• UD-ULTC4k, $220 on Amazon - 2 DisplayPort ports that support 4K60 over DisplayLink, 1 HDMI port that supports 4K30. 60W Power Delivery, 4 USB-A 3.0 ports, 1 downstream USB Type-C port, 3.5mm audio jack.

Note that Plugable mentioned that their Ethernet ports are limited to 300Mbps on macOS due to driver issues. I’m unsure if that extends to all DisplayLink docks.

Alogic also has a few options:

• DX3, $250 on Amazon - 3 DisplayPort ports with DisplayLink, 100W Power Delivery, 3 USB-A ports, 1 USB-C port, Micro SD and SD card reader, Gigabit Ethernet port, 3.5mm audio jack.
• DX2 - 2X DisplayPort ports, 65W Power Delivery, 3 USB-A ports, 1 USB-C port, Micro SD and SD card reader, Gigabit Ethernet port, 3.5mm audio jack.
• Universal Twin HD

Targus has several docks with DisplayLink:

• DOCK190, $310 - 2 DisplayPort/HDMI ports (only 2 video ports can be used at the same time), 100W Power Delivery, 4 USB-A, 1 USB-C, Gigabit Ethernet, 3.5mm audio jack. Thunderbolt alt mode is supported.
• DOCK570, $415 - 4 DisplayPort/HDMI Ports, 4 USB-A, 1 USB-C, Gigabit Ethernet, 3.5mm audio jack. Thunderbolt alt mode is supported.

Kensington has four docks with DisplayLink:

• SD4700P, $250 - 1 DisplayPort, 1 HDMI port (both limited to 2K resolution), 60W Power Delivery, 5 USB-A, 1 USB-C, 1 Gigabit Ethernet, 3.5mm audio jack. Supports up to 5Gbps.
• SD4750P, $290 - 2 DisplayPort/HDMI ports up to 4K60, 85W Power Delivery, 5 USB-A, 1 USB-C, 1 Gigabit Ethernet, 3.5mm audio jack. Supports up to 5Gbps.
• SD4780P - 2 DisplayPort/HDMI ports up to 4K60, 100W Power Delivery, 5 USB-A, 1 USB-C, 1 Gigabit Ethernet, 3.5mm audio jack. Supports up to 10Gbps.
• SD4900P $320 - 3 DisplayPort/HDMI ports up to 4K60, 60W Power Delivery, 5 USB-A, 1 USB-C, 1 Gigabit Ethernet, 3.5mm audio jack. Supports up to 10Gbps.

StarTech has 4 docks with DisplayLink:

• DK30CH2DEP - 2 DisplayPort (4K60), 1 HDMI port (4K30), 100W Power Delivery, 4 USB-A, 1 USB-C, 1 Gigabit Ethernet, 3.5mm audio jack.
• DK30C2DPEP - 2 DisplayPort/HDMI (4K60), 100W Power Delivery, 3 USB-A, 1 USB-C, 1 Gigabit Ethernet, 3.5mm audio jack.
• DK30C2DPPD - 2 DisplayPort/HDMI (4K60), 60W Power Delivery, 3 USB-A, 1 USB-C, 1 Gigabit Ethernet, 3.5mm audio jack.
• DK30CHDDPPD - 1 DisplayPort (4K30), 1 HDMI (4K30), 60W Power Delivery, 4 USB-A, 1 USB-C, SD Card slot, 1 Gigabit Ethernet, 3.5mm audio jack.

Dell has some docks with DisplayLink technology, but they don’t list compatibility with Macs, so probably safest to avoid them unless you’re able to try them first.

Caldigit docks are highly regarded but don’t contain DisplayLink chips. This means you can’t run multiple displays on them. However, they seem to work if you only need a single external display on an M1 Mac, or purchase a USB display adapter. There is a video of someone using a Caldigit TS3 Thunderbolt dock with 4 DisplayLink USB adapters.

Disclaimer

I’m not an expert on any of this, I’ve just read a lot and compiled it into one place. Please let me know if I’ve missed something or if you have any suggestions.

Summary

There are lots of moving parts involved with picking a USB-C dock, let alone one also running DisplayLink. You need one which:

• Supports DisplayLink.
• Supports the number of displays you have, at the resolution and refresh rate you want.
• Has enough USB ports to support other peripherals, or is reliable enough to add a USB hub.
• Supports USB Power Delivery with your laptop, with enough wattage.
• Has enough bandwidth for all your devices.
• Doesn’t have audible fan noise.
• Works reliably and doesn’t cause other issues.

As you can tell from the number of limitations mentioned throughout this post, picking a dock that works with your setup is far from a simple task. I recommend checking the specs closely, checking out reviews, and ideally trying it out at home before committing.