Question Connecting two external monitors to Macbook Pro

Ferguson9

Active Member
Hi,

I have a MacBook Pro (13-inch, 2018, Four Thunderbolt 3 Ports) and I'm trying to connect two external monitors (Dell P2719H) with a Lenovo Thinkpad docking station which has 2 x DisplayPort, 1 x HDMI, USB-C. I think it might be the Lenovo 40AF0135UK.

When I connect them they both turn on fine but when I go to the Display preferences on my MacBook Pro it only shows two displays, my MacBook Pro and one external monitor. Both monitors turn on and mirror each other. I want to be able to close my MacBook and use the two external monitors as two separate displays.

I've googled and some people have suggested that I might need to download a DisplayLink driver? I've tried this but it just says No monitor detected.

I'm running macOS Big Sur.

Can anyone help?

Thanks
 
Last edited:

kyle123

Standard Member
I don’t think there’s a reliable way of getting this working (ive never managed anyway). The display link software is buggy and it’s emulating a second monitor rather than the Mac driving it directly, I’ve done it in the past and the other monitor can be laggy and I’ve always had issues with mouse movement.

USB-C to dual hdmi adapters are cheap and readily available, however, apple in their infinite wisdom decided not to implement the protocols to support this, so they only work on windows - unless you want to mirror (as you’ve discovered) - much to the amusement of my pc using colleagues in the office!

I ended up with 2 usb-c hubs plugged into two ports with an HDMI in each, that works fine at least 🤷🏼‍♂️

I’m told a proper thunderbolt 3 dock supports this, but I can’t confirm it, and I can’t really justify the cost vs 2 cheap usb-c adapters
 

EndlessWaves

Distinguished Member
Yeah, there's a few different ways hubs like this can work internally and the only one well supported by Apple/Mac OS is the most expensive.

The most common sort on newer hubs is using a USB/Thunderbolt feature called DisplayPort Alt Mode which is a standard video output. The DisplayPort protocol has an optional feature called MST which allows you to hook up multiple screens to one output, which is what the multi-port docks use.

Apple does support DisplayPort alt mode but they don't support MST so you'd need to connect the two displays to USB-C/Thunderbolt ports individually.

The other way to do it is to have an external graphics card connected via a data connection - USB or Thunderbolt.

The USB ones are cheaper and more common, although they're not quite as snappy as a full video output. The most well known technology for this is DisplayLink. Apple made some OS security changes a few versions ago which prevented these from working. While DisplayLink has gotten it working again, it apparently isn't 100%.

I believe the thunderbolt ones connect and work fine - thunderbolt provides the same connection as internal graphics cards use - but they're the most expensive.


From the behaviour you describe it sounds like yours is primarily an MST dock, and it sounds like it either doesn't have USB graphics device functionality (some can operate both ways), or it's not using a DisplayLink chip.

Your cheapest option is to plug the second display into a Thunderbolt port on the laptop, a cable is only a few quid.
 

Ferguson9

Active Member
Yeah, there's a few different ways hubs like this can work internally and the only one well supported by Apple/Mac OS is the most expensive.

The most common sort on newer hubs is using a USB/Thunderbolt feature called DisplayPort Alt Mode which is a standard video output. The DisplayPort protocol has an optional feature called MST which allows you to hook up multiple screens to one output, which is what the multi-port docks use.

Apple does support DisplayPort alt mode but they don't support MST so you'd need to connect the two displays to USB-C/Thunderbolt ports individually.

The other way to do it is to have an external graphics card connected via a data connection - USB or Thunderbolt.

The USB ones are cheaper and more common, although they're not quite as snappy as a full video output. The most well known technology for this is DisplayLink. Apple made some OS security changes a few versions ago which prevented these from working. While DisplayLink has gotten it working again, it apparently isn't 100%.

I believe the thunderbolt ones connect and work fine - thunderbolt provides the same connection as internal graphics cards use - but they're the most expensive.


From the behaviour you describe it sounds like yours is primarily an MST dock, and it sounds like it either doesn't have USB graphics device functionality (some can operate both ways), or it's not using a DisplayLink chip.

Your cheapest option is to plug the second display into a Thunderbolt port on the laptop, a cable is only a few quid.

Thanks for your reply. I've used an adaptor as you suggested to plug the second display directly into the thunderbolt port on the laptop. This seems to work.
 

IWC Dopplel

Distinguished Member
I ended up needing a high spec MacBook Pro or run two 5k screens, works well but did require a good vide card and a top spec unit
 

Suki10

Standard Member
Currently my setup to connect my MBP 2017 to two Dell Monitors are:

1 x Dell D6000 Universal Dock
1 x MBP 2017
2 x Dell Monitors
1 x USB C to HDMI cable

I downloaded the DisplayLink driver and connect the D6000 to my Mac using the USB C cable from the Dock. I then use one DisplayPort cable from the dock into one of the monitors. For some reason if I use two DisplayPort cables, one going into each monitor from the dock, it only mirrors and not extends. So I use one DisplayPort cable from the dock into Monitor 1, and one USC C to HDMI Cable running directly from my Mac to Monitor 2. This then extends my display and I have my Mac running on two external montiors.
 

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