Docking station MacBook Pro M4 Max

Macs which have the ability to drive multiple 4K displays over USB-C or Thunderbolt can generally drive

• One 4K display using a USB-C (DisplayPort) adapter or a "plain" USB-C dock
• Two 4K displays using a Thunderbolt hub/dock

There are a few Thunderbolt docks whose vendors claim that they support three or four displays. I know, because these are the ones that keep popping up in threads saying "I connected two monitors to this Thunderbolt dock but can't get them to run in extended display mode."

My guess would be that Thunderbolt 3 and 4 docks that support three or four displays are using the equivalent of DisplayPort MST daisy-chaining … something that Macs don't support. If that guess is correct or close enough, it might still be possible to use one of those docks to run two displays in extended desktop mode. But only with the "right" combinations of video output ports.

That Asus dock has two HDMI v2.1 ports, and a Thunderbolt 4 daisy-chaining port. If you're using the two HDMI ports now, and can't get extended display port mode to work, that suggests that the dock might be driving both HDMI ports from one DisplayPort session in a DisplayPort MST daisy-chaining sort of way.

You could try

• Connecting one monitor to the dock's HDMI 1 port, using a HDMI to HDMI cable.
• Connecting the other monitor to the dock's Thunderbolt 4 daisy-chaining port, using a USB-C to HDMI adapter cable

No guarantees - but it just might work.

that appears to be a 1920 by 1080 display

with DisplayPort 1.2 and

HDMI 1.4 inputs

you can connect one display with an HDMI cable directly from the HDMI output of the computer, PROVIDED, you use a certified cable that is marked "PREMIUM" or "ULTRA" spec.

You can connect one display with the adapter/cable you have, USB-C to HDMI, or you could use an adapter/cable USB-C to DisplayPort, PROVIDED, the cable is ONE meter or shorter.

In order to connect more than one display to a Dock, the output port, the Cable, and the first device (Dock or Display) must be a genuine ThunderBolt. USB-C has fewer data pathways and less capacity, so a USB-C Dock can not be used on a Mac for more than ONE display.

Grant Bennet-Alder wrote:

In order to connect more than one display to a Dock, the output port, the Cable, and the first device (Dock or Display) must be a genuine ThunderBolt. USB-C has fewer data pathways and less capacity, so a USB-C Dock can not be used on a Mac for more than ONE display.

The OP is using a genuine Thunderbolt dock. I'm guessing that the issue is that this Thunderbolt dock supports more than two displays – and to do that, is using MST in some way that Macs do not support.

The user manual seems to offer possible confirmation of this. Unfortunately, this is all the detail that it seems to provide.

ASUS – ASUS Triple 4K Thunderbolt™ 4 Dock - User Manual

"As some notebook models do not support MST function or have limited bandwidth for display, please check with the device manufacturer for more details."

ThunderBolt-4 is optimized for connecting multiple ThunderBolt devices or Docks. It allows a small amount of local devices, then allocates the majority of its bandwidth to the connection of three more ThunderBolt Docks or devices.

This OWC video article explains the subtle difference:

https://eshop.macsales.com/blog/87800-whats-the-difference-between-thunderbolt-3-and-thunderbolt-4/

the punchline:

Because of the difference in how Thunderbolt 4 allocates data, every port on a Thunderbolt 4 device that isn’t Thunderbolt must share a single 10GBps slice of USB bandwidth.

.

Wishmaster40 wrote:

I have ordered a new docking:

iVANKY FusionDock Max 1 and just to be sure 2 cables of UGREEN 4K USB C (Thunderbolt 3) to HDMI cable.

Ivanky – FusionDock Max 1

I never heard of this brand before in my life.

Two things in this dock's description jumped out at me right away: "NOT compatible with PC or Intel MacBooks" and "Quad Display Setup".

This may be a Thunderbolt dock, but if it is another one that promises the ability to attach more than two displays, my guess would be that it uses MST in some way that Macs do not support, and that you will probably be in much the same boat you are now.

EDIT: After looking further down the description on the vendor's page, I see that the vendor says "And for the power users with beefiest Apple silicon MacBook Pro, behold the magic of three 6K and one 4K displays, all in harmony." So maybe they're doing something else that would work.

And if all this falls then I just will have to but new monitors, does anybody has experience with the Samsung 27” High Resolution 5K Monitor S90PC?

Samsung – 27" ViewFinity S9 5K IPS Smart Monitor with Matte Display, Ergonomic Stand and SlimFit Camera

That monitor has 5120x2880 (5K) resolution. Unless you're using a Thunderbolt 5 docking station and the extra bandwidth of Thunderbolt 5 changes the "rules", you'd need to hook up each of these two monitors to a different Thunderbolt port on your M4 Max MacBook Pro.

Wishmaster40 wrote:

Do you know why Ivanky needs to connect 2 USB-C ports using just 1 cable?

Maybe two upstream ports means that they – in effect – stuffed two Thunderbolt docks into one box. If there are two Thunderbolt connections running from the computer to the dock, with each carrying up to two embedded DP sessions, that might explain how they could get support for up to four monitors.

what make&model display(s) are you connecting?