Mac mini monitor constantly turning off and on after updating to Big Sur 11.4

Pablogp79 Said:

"Big Sur 11.4 issues: Hi, after upgrading to Big Sur 11.4 on my Mac mini, my monitor started turning off and on constantly. Please help."

-------

Seems Ports Aren't Working:

Try the following, in the order provided...

• Boot in Safe Mode:

[Hold Down: shift key, upon boot], In Safe Mode, Login Items do not run at login, certain preferences are set aside, and damaged system files are then reset. So, once booted in to Safe Mode, wait for 30 seconds, and then boot up normally, attempting another connection.

• Try a New Admin User:

What happens when you create a new administrator user, and log int it? Do you still get this error? If not, then it is likely an error with the current user. If so, then it is likely an error with your macOS.

• Reset the SMC and your NVRAM:

Sometimes when changes are made to the system(i.e. Updates), system configurations (i.e. for Ports) become manipulated, technically. So, reset the SMC and NVRAM. Try performing each thrice. It may take sometime, being certain you have the time to perform these resets.

Pablogp79 Said:

"Big Sur 11.4 issues: Sorry, that did not work. My monitor still get blackout randomly"

-------

Some Other Things to Try:

A. Using Monitors:

What happens when you try this monitor on another computer (yours or a friends - with their permission, or course)?. Also, what happens when you connect a different monitor? Any differences when either is performed?

B. Remove Login items:

See if any of these apps are a Login Item. If so, remove them as such and then restart the Mac, seeing if it/they no longer load(s) at login.  Go Here: Change Users & Groups Login Items Preferences on Mac - Apple Support.

C. Scan your Mac for Malware: 

Use MalwareBytes for Mac --- This is software that searches for malware/adware. So, scan with it and then remove what is found. Once removed, uninstall MalwareBytes for Mac. Then restart the Mac. Malwarebytes is made by longtime users of these forums, making it the onlySecurity Software reliable for Macs.

Downloads:

1. Malwarebytes Anti-Malware for Mac
2. Malwarebytes Uninstaller

D. Single Out this User:

For temporary user, create a new administrator, seeing if you still get this error. If so, then it is an error in the macOS. If so, then it is an error with the current user. So, what you would do is trasnfereverything over to this new user, and then trash this current user.

E. Reinstall the macOS:

Nothing would be deleted. It's just that items that have become corrupted or deleted, would be replaced or reinstalled back to where they should be. Go Here: How to reinstall macOS from macOS Recovery - Apple Support. Important: Be certain to create a backup of your Mac prior to all of this. That way, you can have something to restore from the Mac from, should anything go wrong with the reinstall.

F. Restore from a Backup:

Do you have a Time Machine Backup of your Mac that you created prior to this? If so, restore form it. If not, take this as a learning experience, knowing to always create a Time Machine backup of your Mac prior to making any major change to is (i.e. macOS upgrade), so that you can have something to restore your Mac from, should anything go wrong with the upgrade.