S2725QC, Mac mini, insane colors

The 2725QC worked fine with the M4 MacMini and MacOS 18.

No problems with using the monitor as an external screen with an M1 MacBook Air, even after OS updates.

I think there is some confusion here. 18 refers to an iOS iPhone OS update, not the MacBook macOS OS.

Based on your troubleshooting, the problem is specifically the Mac mini M4 and macOS 26 Tahoe update, not the monitor. Post the issue on the Apple Forum to get their opinions.

Monitor + M4 MacMini + MacOS 26.0.1 + USB-C cable = insane colors

Monitor+ M1 MacBookAir + MacOS 26.0.1 + same USB-C cable = working fine

And everything was working ok on both the MM and MBA before the OS update.  Only the MM now has a problem.

There is/was one difference.  I had installed DDPM on the MacMini but not on the MacBookAir.  I removed it today but it didn't help.  However, in looking at the DDPM logs, I see all kinds of fatal errors on the current log that don't appear on previous logs (when the monitor was working ok).

Logic says the issue is related to DDPM.  Even though I removed the DDPM activation file, and turned DDI/CI off on the monitor itself, I think this is where the problem is.  I've also had the issue of being unable to update DDPM 2.1.1.0004.  I can download 2.1.1.0007 but when I get the popup message asking if I want to install it, the Yes button doesn't do anything.

If I post the DDPM log here, or in an email, would that be helpful?

I just checked.  There are 46 fatal errors listed in the DDPM log after the MacOS was updated.  In the day before the update there are 0 fatal errors.  Oh, and I should note that when I did have DDPM activated, I was able to see it as a popup screen and was able to make changes.

So you uninstalled DDPM 2.1.1.0004 and restarted the MacMini. Re-enabled DDC/CI on the S2725QC. Then downloaded DDPM 2.1.1.0007 from HERE and saved it to the MacMini desktop. Then you are running it from there?

I have DDC/CI turned off.  I downloaded DDPM 2.1.1.0007 from the Dell website and see the zip file.  However, I haven't been able to activate it.  I get a popup screen asking if I want to but the Yes button doesn't do anything.

Given that I have DDC/CI turned off, I thought that should prevent any program such as DDPM from affecting the monitor.

All of the 46 fatal errors in the DDPM log says Communications Error, such as:

2025-10-05 20:58:01.021 [913:179850] ERROR UP_API:HelperWriteEx-WriteI2C FATAL Communications Error. Disconnected?
2025-10-05 20:58:01.021 [913:179850] ERROR UP_API:SetDDCCICommand()-FAILS => 4
2025-10-05 20:58:01.126 [913:179850] DEBUG UP_API:DisconnectMonitor()

Confused. DDPM 2.1.1.0007 cannot install correctly IF DDC/CI is turned off. It has to be turned on prior to installation. Then reboot the PC. Then retest.

OK.  I turned DDI/CI on.  I think I've installed 2.1.1.0007.  I used the 0007 file and went through the installation process, which completed.  However, Control-Shift-D doesn't bring up the popup screen, which worked ok with 2.1.1.0004, so I'm not certain whether 0007 is really installed or not.

Either way, colors are still insane after restarting the computer.

Connect the S2725QC and same USB-C cable to the M1 MacBookAir then install DDPM 2.1.1.0007 on the M1 MacBookAir. Do the colors still appear OK?

@DELL-ChrisM2​ 

Thanks, but I want to keep at least one computer that works ok with this monitor. I'm not going to risk that. :-)

I think my next move is to rip out every file I can find related to DDPM and see if that solves it.  I never should have installed it to begin with.  I'm comfortable with the OSD joystick and don't need a software option.

You haven't reacted to my comments about the fatal communications errors in the post update DDPM log.

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It says I've exceeded the number of allowed messages, so I'm doing this reply as an edit.

@DELL-ChrisM2​ 

As I wrote, before the MacOS update the 2.1.1.0004 logs show 0 fatal errors and the monitor was working well.  After the update the logs show 46 fatal errors and the colors go insane.

Simple logic says there's something in the DDPM program that doesn't work either with the update process itself (since it also happened with the 18 to 26 MacOS update) or something specific within MacOS 26.

There's also the oddity that I was able to correct the problem a few weeks ago using Self Diagnostic when updating from OS 18 to 26.0.0.  Now that doesn't fix it after the update to 26.0.1.

I do not have access to what/why those Communications error happened. All I can do is notify the team of this thread.