Mac Mini M4 Pro & Dell TBS19 Dockingstation

The displays need to be connected directly to the new Mac mini to insure proper detection and then a handshake.

loeberjens wrote:

The issue is now that the Mac Mini is not recognizing the U3419W Display, only the U2518D is working on full resolution, the curved display is mirroring the picture with reduced resolution. I thought that the Mac Mini M4 Pro can AT LEAST handle that amount of displays? (Had a MacBook Pro M1 before, here we had the limitation regarding only 1 external monitor, that's why i purchased the M4 Pro now.

The M4 and M4 Pro Mac minis can both support up to three external displays, depending on the resolutions and refresh rates of the displays.

As per Apple, the Mac Mini can handle at least 2 4K Displays - are there limitations with the TB Dock and Apple? I found the KB Article related to the TB Dockings from Dell, but i thought the issue is fixed now?

You can only connect two displays to a single Mac host port if the Mac supports multiple displays, and the device immediately connected to the Mac is a Thunderbolt device (like a Thunderbolt dock).

Dell Thunderbolt Docks and Apple USB-C Hosts | Dell US

Any recommendation regarding that issue?

It sounds like this Dell Thunderbolt dock uses the equivalent of DisplayPort MST daisy-chaining – something that Macs do not support. So while you can connect two monitors to it, and drive them from your M4 Pro Mac mini in extended desktop mode, you can only do so if you use certain combinations of ports on the dock.

Figure 2 of the "Dual Monitor Setup" section of the Dell Support article seems to say that in order to get extended displays, you must connect one display to a Thunderbolt port on the dock.

Dell Support – Dell Thunderbolt Dock – WD19TBS

Dell – Dell Docking Station WD19TBS Thunderbolt User Guide

My interpretation of this is that when you use this dock with a Mac, all of the following ports (shown on page 9 of the User Guide) will run off the same DisplayPort "session" in an unsupported, MST-style fashion:

• Both of the DisplayPorts (shown as Port 1)
• The HDMI port (shown as Port 2)
• The USB 3.2 Gen2 Type-C port with DisplayPort 1.4 (shown as port 3)

You can use any of them that you like, but if you use two or more, the attached displays will only mirror each other.

Port 7 ("Type-C with Thunderbolt 3 port") presumably supports USB-C (DisplayPort Alt Mode) displays & adapters using a separate Thunderbolt-encapsulated DisplayPort session. So if you hang one of your displays off of it, then your displays will be running off different signals from the Mac, and you will be able to get extended desktop mode to work.

Would it be helpful to invest in a second USB-C capable Monitor (to exchange the 25" one) or are they Thunderbolt Docks out there who can handle that setup with BOTH Mac and PCs?

As far as getting extended desktop mode to work, it sounds like the key thing is to plug one of the displays into the Thunderbolt port on the dock.

It sounds like port 3 and port 7 can both support USB-C (DisplayPort Alt Mode) displays and adapters. But there is a key difference. When you're using the dock with a Mac, a display plugged into port 3 will be attempting to use the SAME signal as displays plugged into the DisplayPorts or HDMI ports. One plugged into port 7 will be attempting to use a DIFFERENT one. So even though a plug might physically fit in both places, and you might get video from both places, one place will support extended desktop use and the other won't.

Since this is a Dell product, best to contact them. Good luck!