[GH-ISSUE #248] Two Macs into same monitor (HDMI1 and HDMI2) - MonitorControl only works on one #190

New issue

Closed

opened 2026-05-05 05:22:28 -06:00 by gitea-mirror · 3 comments

gitea-mirror commented

2026-05-05 05:22:28 -06:00

Owner

Originally created by @emily-pesce on GitHub (Jul 7, 2020).
Original GitHub issue: https://github.com/MonitorControl/MonitorControl/issues/248

I have 2 Macs both running 10.15.5:
Mac mini (2018)
MacBook Pro (13-inch, 2017, Two Thunderbolt 3 ports)

The monitor is: LG 27UD68. Both computers go into monitor via HDMI. I use the same monitor and switch between the inputs when I need to use one or the other.

Both computers have the requested accessibility function selected.

MonitorControl on the MacBook Pro correctly adjusts brightness (it's amazing, thank you!).
Nothing happens when I move the slider on the Mac mini. Has no effect.

I am baffled. Any ideas?

Originally created by @emily-pesce on GitHub (Jul 7, 2020). Original GitHub issue: https://github.com/MonitorControl/MonitorControl/issues/248 I have 2 Macs both running 10.15.5: Mac mini (2018) MacBook Pro (13-inch, 2017, Two Thunderbolt 3 ports) The monitor is: LG 27UD68. Both computers go into monitor via HDMI. I use the same monitor and switch between the inputs when I need to use one or the other. Both computers have the requested accessibility function selected. MonitorControl on the MacBook Pro correctly adjusts brightness (it's amazing, thank you!). Nothing happens when I move the slider on the Mac mini. Has no effect. I am baffled. Any ideas?

gitea-mirror

2026-05-05 05:22:28 -06:00

closed this issue
added the
duplicate
label

gitea-mirror commented

2026-05-05 05:22:34 -06:00

Author

Owner

@JoniVR commented on GitHub (Jul 9, 2020):

Can be the case due to different cables (one not supporting DDC) or different GPU's.
Try swapping the cables and then see if the one that didn't work before works. If you have a displayport layout around try that as well.

See: https://github.com/MonitorControl/MonitorControl/wiki/Monitor-Troubleshooting

@JoniVR commented on GitHub (Jul 9, 2020): Can be the case due to different cables (one not supporting DDC) or different GPU's. Try swapping the cables and then see if the one that didn't work before works. If you have a displayport layout around try that as well. See: https://github.com/MonitorControl/MonitorControl/wiki/Monitor-Troubleshooting

gitea-mirror commented

2026-05-05 05:22:36 -06:00

Author

Owner

@damoen commented on GitHub (Jul 20, 2020):

I am facing a very similar issue, also with Mac Mini (2018). See #265

@damoen commented on GitHub (Jul 20, 2020): I am facing a very similar issue, also with Mac Mini (2018). See #265

gitea-mirror commented

2026-05-05 05:22:38 -06:00

Author

Owner

@JoniVR commented on GitHub (Aug 14, 2020):