Since last week my extended monitor stopped working in mac mini M4. I have installed again the Operational System and it continued the problem.
Today I went to a Mac Office and we tried different approaches. The conclusion was that using two monitors, an Samsung and a LG, it not worked. But a Philco from the Office with my Sambung is ok and a Philco from the Office with my LG. My monitors are fighting each other.
Mac mini, macOS 26.4
Thank you for updating that info.
The latest macOS update has crippled the use of most long cheap manufacture supplied cables.
I would move the 22" LG to the Mac mini's HDMI port using a short high speed HDMI cable.
for examples:
https://www.amazon.com/8K-HDMI-Cable-Highwings-Braided/dp/B08NX5CZTF/ref=sr_1_3?
https://www.amazon.com/dp/B09M89C7MX/ref=sspa_dk_detail_0?
Then I would put the 27" Samsung on a USB-C port using a short high speed USB-C to HDMI cable.
for examples:
Thank you for updating that info.
The latest macOS update has crippled the use of most long cheap manufacture supplied cables.
I would move the 22" LG to the Mac mini's HDMI port using a short high speed HDMI cable.
for examples:
https://www.amazon.com/8K-HDMI-Cable-Highwings-Braided/dp/B08NX5CZTF/ref=sr_1_3?
https://www.amazon.com/dp/B09M89C7MX/ref=sspa_dk_detail_0?
Then I would put the 27" Samsung on a USB-C port using a short high speed USB-C to HDMI cable.
for examples:
You’re welcome.
You might actually get by with one upgraded cable for the 27” Samsung display. Then use your best HDMI cable for the 22” LG.
External drives are not as critical as displays, but you should toss any long thin poorly shielded USB cables in trash. Plus you may need to limit the number of USB portable drives that are connected to the Mac mini at the same time.
Please provide detailed info about those displays and how each is connected to the Mac mini.
1) What model is the Samsung and how is it connecting to the Mac mini...?
2) What model is the Dell and how is it connected to the Mac mini...?
for reference:
see "Display Support" at > Mac mini (2024) - Tech Specs - Apple Support
Samsung Model S27DG300EL connected through direct HDMI cable to Mac Mini HDMI connection
LG Model 22MP410-BB.AWZUMVZ connected through to Mac Mini USB-C port.
Mac Mini recognizes both monitors through different connections only individually. With both monitors together is is not recognizing anymore.
At the Local Support I have tried connections with a other monitor Philco (I don't know the model) and both monitors could work together with this Philco Monitor.
Samsung and LG are no more working together and it happened only last week. I have bought Mac Mini on June of 2025 and since then I have been working with these two monitors.
Thanks. I will study which solution is better. Another thing that happened is that my externals expansion memories started to fail maybe because the same reason: cable quality.
Mac mini M4: Samsung/LG dual monitor issue
