What is a “Slow Link” in GPO?

I think every sysadmin that handles GPOs should know what Slow Link is. It can be tricky troubleshooting certain scenarios, and not knowing what a slow link is.

Table of Contents

1. What is a slow link?

Before applying a GPO, the client machine measures the throughput between the client itself and the nearest Domain Controller. This is to determine if the link between the client and DC is considered “slow”.

If the link is considered slow, certain GPO settings will not be applied. This is done to save bandwidth, and certain settings could slow down the startup process, making it a horrible experience for the end user.

The default threshold is 500 kb/s, so any link with throughput below that is considered slow.

2. How to change the default 500 kb/s (or disable slow link)

User/Computer > Policies > Administrative Templates > System > Group Policy > Configure Group Policy slow link detection.

If you change the value to 0, slow link detection will be turned off.

3. What settings won’t be applied when the link is considered slow?

Here is a table, describing what settings by default will be applied, and those that will not:

FeatureApplied
Administrative TemplatesYes
Group Policy PreferencesYes
SecurityYes
802.3 Group PolicyYes
EFS RecoveryYes
IE maintenanceYes
Internet Explorer Zone MappingYes
IP SecurityYes
QoS Packet SchedulerYes
Microsoft Offline FilesYes
Software Restriction PoliciesYes
Windows Start MenuYes
WirelessYes
Deployed Printer ConnectionsNo
Disk QuotasNo
Folder RedirectionNo
ScriptsNo
Software InstallationNo

4. Can I choose to configure if a feature will be applied or not?

Yes!

In the Group Policy folder (User/Computer (You might need to change it both places) > Policies > Administrative Templates > System > Group Policy) there is a lot of settings that are named “Configure x policy processing”. Here you can configure if a specific feature should be processed, even if a slow link is detected.

E.g. if I want to enable Folder Redirection even though the link is considered slow, you would configure the “Configure folder redirection policy processing” as shown in the picture above.

I think you can also do it the other way around, all though I haven’t tested it. If you want to disable “EFS Recovery” when a slow link is detected, you could enable “Configure EFS recovery policy processing” and then NOT clicking the “Allow processing across a slow network connection”. As mentioned, I have not tested this, but I think it makes sense. Let me know in the comments, if you actually have tried this 🙂

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