Network Connection Failed [-8]

Hello,
Operating system deploument is completed by SCCM and Zscaler Client connector 3.1.0.129 installed during the OSD.
User Sign in to the computer and Internet is not working. Because Zscaler is not logged in and below message appears. It is tried with differenet account as well. But it does not work.
Network Connection Failed [-8]

Please help.

Hello. First that version if quite old. Have you tried a more recent ZCC release? Also, have you looked over the following installation options - Customizing Zscaler Client Connector with Install Options for EXE | Zscaler

Do you have Strict Enforcement enabled? Customizing Zscaler Client Connector with Install Options for EXE | Zscaler

Check if the firewall or router or proxy in between.
Ensure below connection are get through from the machine where ZCC installed.

Config | Zscaler cloud name/zscaler-app
example :: your cloud name — zscaler.net