Diagnosing Network Isolation Issues

Dear Will,

we are using the O365 Suite including Teams in combination with Zscaler Client Connector for Internet Access, which brings a local Proxy to each of our clients that listens on 127.0.0.1 Port 9000

We are experiencing the behavior that Outlook, Teams and other Office APPs can’t connect.

Only the installed applications of Outlook, Teams, OneDrive, OneNote and so on are affected – the Browser versions work fine.

Additionally we see blocks in the Windows Firewall Log to 127.0.0.1 port 9000 and we also see Security Eventlog entries from WFP similar to yours above.

On one problematic client we executed the following command which immediately solved the issue resulting in Outlook and Teams starting to work.

CheckNetIsolation.exe LoopbackExempt -a -n=”microsoft.aad.brokerplugin_cw5n1h2txyewy”

The issue described in this article mostly matches our issue and led us to the command above:
https://community.zscaler.com/s/question/0D54u00009evn2FCAQ/win10-unable-to-access-loginmicrosoftonlinecom-via-zapp

So my question now is:
Is this really our way to go? We would have to script it somehow to deploy it to our approx. 5000 clients.
You mention in your article that using the command is

“intended for debugging purposes only.”

Any Feedback or further information is highly appreciated.

Thanks in advance

Greetings

Patrick