Network Link Conditioner not working on macOS Sierra

After installing the newest version of Network Link Conditioner on macOS Sierra, it doesn't appear to work. It has no effect on my network connectivity, even when set to 100% loss. Anyone experience this? Is this simply a case of Apple not updating NLC for Xcode 8?

This issue is fixed in the latest version of the Network Link Conditioner - it's in the "Additional Tools for Xcode 8.1" download from https://developer.apple.com/download/more/.

I've tested all the built-in profiles and they work as expected.

I can't comment (not enough reputation), but figured I'd add that the Xcode 8 tools that have the Network Link Conditioner in it has changed names.

https://developer.apple.com/download/more/

It's now in the "Additional Tools for Xcode 8", instead of "Hardware IO Tools for Xcode 7.x".

Though, that didn't fix any of the issues...

Step 1: Uninstall Old NLC by right clicking ("remove") it in "System Preference"

Delete Network link conditioner

Step 2:

Open https://developer.apple.com/download/more/ , login to apple account and search for additional tools and Download Additional Tools for Xcode 9.

Tested default and my existing custom profiles, all worked like a charm!

Selecting the "High Latency DNS" profile works for me. This is not always what I want, but better than nothing.

I found a workaround that made it work for me.

Step 1: Enable pf

sudo pfctl -e -f /etc/pf.conf

Step 2: Open link conditioner and enable a rule

Step 3: Check if there are dummynet rules in pf

sudo pfctl -sa

You should see a line like:

dummynet-anchor "com.apple.nlc" all

If you disable pf with pfctl -d then link conditioner stops working and you have to disable all link conditioner rules and make the above steps.

It worked for me very well.

Easy way to test if it's working is to enable DNS Latency and test it with:

nslookup www.google.com

If you installed link conditioner for previous Xcode version it will not work with Xcode 8. You can download Additional_Tools_for_Xcode_8.2.dmg from http://developer.apple.com/download/more/

then you will need to move the old link conditioner before installing the new one. Like this:

sudo mv /Library/PreferencePanes/Network\ Link\ Conditioner.prefPane/ ~/old

Then double clicking on link conditioner will ask you to install it.

Installing an older version of Network Link Conditioner (NLC) can solve the issue.

1. Uninstall NLC by right clicking it in "System Preference" and choosing "… remove"
2. Download an older version of NLC from <https://developer.apple.com/download/more/>;. (Search for bundles named "Additional Tools for Xcode …")
3. Install NLC from the downloaded bundle and try it out. (http://www.netmeter.eu can help you testing your network speed)

In my case I was using OS X El Capitan Version 10.11.6 . The NLC from the newest bundle "Additional Tools for Xcode 8.2" did not work for me. But NLC from "Additional Tools for Xcode 7.3" works like a charm. Reinstalling or changng Xcode is not necessary.

Installing of Network Link Conditioner from "Additional Tools for Xcode 9 beta" worked for me.

For XCode 10.2, in More developer tools - Additional Tools for XCode 10.2, you will find Network Link Conditioner.