I have a 2019 Macbook Air and I use a QGeeM USB-C hub to connect to an ASUS 28" 4k monitor. The Monitor has a DP port and and 2 HDMI ports - one for 4K @ 30Hz and the other 1080p @ 60Hz. I connect to the HDMI port that supports 4k @ 30Hz. I use a Logitech keyboard with the USB dongle connected to the hub. And an Apple bluetooth trackpad. I leave the macbook screen/lid closed and connect to the hub.

98% of the time the 4k resolution on the monitor works perfectly. Every once in a while, the 4K monitor loses its resolution and I can only get 1080p. Sometimes, I can just restart the macbook, unplug and replug the display HDMI cable and everything works fine. And sometimes I end up spending an entire day trying to fix this.

I don’t understand why this happens and more importantly, How might I fix this ?

  • There is a system utility that I have heard does a good job of switching resolution on the fly. SwitchResX at madrau.com. Though I have never used it myself I continue to read about how good it is Aug 4, 2020 at 15:33
  • Use an active adapter. See this similar case: apple.stackexchange.com/a/354538/119271
    – Allan
    Aug 4, 2020 at 17:16
  • @Allan - I just read through the thread on 'active adapters'. So, when I used (in the past) a mini-DP (on old MBP) to DP port on the monitor, I never had any trouble. Worked perfectly always. The USB-C Hub has an HDMI port so I'm connecting using HDMI cable from the hub to the 4K HDMI port on the monitor. Do I need to replace the HDMI cable for one with an active adapter ? Or do I need to replace the hub with one that has an active HDMI adapter ? Confused. Thanks.
    – Vasuvius
    Aug 4, 2020 at 18:14
  • Yes! Using mDP to DP is the best way because there's no signal conversion. I wrote a lengthy post on HDMI vs DisplayPort. You need to replace the hub with an active adapter as it's likely passive. Also, go with known brands like Anker, Belkin, TrendNet,, etc.
    – Allan
    Aug 4, 2020 at 18:21
  • I'm going to tag this as a dupe since there are many questions already with these same symptoms and solutions. It can be reopened and we can continue chatting to get your problem fixed up.
    – Allan
    Aug 4, 2020 at 18:38


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