How do I stop internet traffic while in sleep on iMac?

Disable “Power Nap” (System Settings > Battery >Options). This reduces background activity, though some services may still use the NIC adn Turn off “Find My Mac” + iCloud services

Need_help_give_help (Author)

Perhaps you need to set up the newer hardware running its most current macOS

and not try to micromanage the computer; instead read and learn about what it

can do.. See system preference/settings and choose wisely.

And the newer Apple Silicon desktop computers have a battery on the board.

..Not used for same as a portable computer, but still there; and that Mac may

need a Diagnostic/repair performed by an Apple authorized service provider..

How to Set your Mac to Use Different Network Connections: Wi-Fi, Ethernet, etc.

https://macreports.com/how-to-set-your-mac-to-use-different-network-connections-wi-fi-ethernet-etc/

The newer model is What? You've not said which build year and model hardware

the device actually is; so that much without any illumination, in a void of details.

The setup for all internet sources and settings is in the system; no matter what.

However the newer model, settings are important. To only that hardware + OS.

An older Mojave system is fair & marginal; while technology moves to elsewhere.

Of my Macs, one runs High Sierra 10.13.6 with Firefox ESR + Brave browsers. It

could run Mojave 10.14.6; if not being a Server model with dual rotational HDDs

it might run Catalina 10.15.7 OK. Older style HDDs won't do with newer formats.

There's resources online, including manuals for macOS & some build year models.

Mac computers with Apple silicon - Apple Support

For the iMac, presumably its the modern hardware and Apple Silicon chip-set.

Integrated memory, cpu and the works, all inside a small segment, of main board.

For whichever one is Portable Mac, those require serviceable good battery inside.

If you see Service Recommended on your MacBook Air or MacBook Pro - Apple Support

Identify your Mac by Model Name and serial number helps widen understanding.

Find your Mac model name and serial number - Apple Support

To learn how to use the settings for best effect, see how to portion for

various Mac computers and/or devices are part of their manuals online.

The 'Help files' inside MacOS can be found from Main menu bar.

Find the 'Getting Started' guide for your Mac - Apple Support

//support.apple.com/guide/mac-help/about-your-mac-model-mchl..

Mac User Guide (Table of Contents) - Apple Support

//support.apple.com/guide/mac-help/toc

How To Setup/Sync Internet Account on macOS [Tutorial] - UMA Technology

https://umatechnology.org/how-to-setup-sync-internet-account-on-macos-tutorial/

..some step by step instructions: where has issues you face varied from the paths?

Sorry for not exactly being of specific help. Once you've organized your question

and figure how to narrow the focus on the issues within hardware & software..

~ You may do better if your questions start anew; ask for help again, differently.

Do you sleep the Mini at night? If so you should shut it down as that will prevent the Mini from coming out of sleep and it also clears out any system and applications temporary cache and swap files. This helps is keeping the Mac's performance top notch.

It takes my Mini M4 about 3 seconds to boot up. Not an inconvenience.

The port indication drops from GbE Gigabit Ethernet to 100 MbE Fast Ethernet? That seems weird. What sort of router (vendor and model) do you have? Current firmware loaded?

As for sleep, this is the expected and usual behavior. If you want it shut down, select shut down, not sleep.

Sleep can be awakened. I haven’t tried a magic packet (for Wake On LAN; WOL) on Apple silicon, but it wouldn’t surprise me that it the packet still works.

If you launch Terminal app and enter the following (benign) command, what is the output? (Post it here.)

pmset -g

Related: Schedule your Mac to turn on or off in Terminal - Apple Support

Need_help_give_help (Author)

Depending on the build model M1 iMac, one was equipped

w/ an Ethernet port, the other one, was not. Other identifier

tells how without starting those up, which one you have..

•Take a tour of iMac - Apple Support

//support.apple.com/guide/imac/take-a-tour-of...2054/2024/mac/15

Yours appears to be an older model, so this might not apply.

Gigabit Ethernet (RJ-45): "..The 24-inch iMac with four ports includes

a power adapter with Built-in Ethernet. The 24-inch iMac with two ports

comes standard with a power adapter, Without built-in Ethernet, but can

be configured with Ethernet ~ at the time of purchase."

"..If you didn’t upgrade to Ethernet, at the time of purchase, a USB to

Ethernet adapter may be required. To use Ethernet, connect a router or

modem to the Gigabit Ethernet port on the power adapter."

Ethernet has advantages in the overall configuration and

use in a local network, too. However my hardware mostly

does not use an Ethernet, & remains tilted to older S/W

and local Wi-Fi between macOS and iOS devices.

Many of the Apple product manuals info are back-linked

in several of their articles, to be sure to note in context.

Need_help_give_help wrote:

Having provided the output of pmset –g I was interested particularly with the line:

Networkoversleep 0

I have searched and cannot find what it is. Is it a possibility that setting it to 1 might be the solution to this thread?

To see what a particular command does and how it works, use man <command> in Terminal.

The manual page for pmset does not indicate what it does with any clarity, but it does note that it cannot be changed by the user:

networkoversleep - this setting affects how OS X networking presents shared network services during system sleep. This setting is not used by all platforms; changing its value is unsupported.

I don't think that has anything to do with connecting to the internet unless you've poked a hole in your router to access the Mac from outside your LAN and you have sharing services enabled.

You can certainly install a remote-managed power switch that can shut down the Mac, or can get some networking gear that disables the port when you want the port disabled.

Maybe a wired keyboard helps.

But otherwise, your requirements are in conflict.

And that port dropping from GbE to Fast is odd.