I have a 2017 MacBook Pro. It has 2 USB-C ports on the left side and I use an Aukey hub to provide more ports (4 USB, 1 HDMI, 1 USB-C) and always to connect two monitors.
I connect one monitor through the hub with the HDMI port and another directly to the MBP with a USB-C adapter. Sometimes when I connect the hub to the Mac and the 2nd monitor to the Mac, it works as it should with no problem…but more than half the time I have to connect, disconnect, jiggle, jangle, switch ports, reconnect HDMI, etc. and hopefully they will both work. OFTEN, I can only get one monitor to fire up.
Is there any kind of software fix or reset that might solve this issue? Any other thoughts welcome. Thanks.
Best Answer
It's not a software fix, but a "hardware" one, that will address this issue.
The problem lies in the fact that the multi-function hub most likely doesn't supply an active HDMI adapter. You can usually get around this limitation with a reboot, but that can become burdensome especially if you go from a desktop setup to a mobile setup multiple times per day.
Why is it a hardware issue?
Clock signals. HDMI has one and DisplayPort (what you're converting from) doesn't. So, when you plug in your HDMI monitor, there's no signal to sync up to. Rebooting usually resolves this and gets everything "synced up again." A passive adapter (what is in the hub) just rearranges the signal whereas an active adapter actually recreates the signal making it much more reliable.