---
title: Troubleshooting connection errors
description: The Sigma application connects to remote servers when checking license (activation, keeping session alive etc.) and when checking updates. If you are experiencing connection errors, have security software blocking internet connection for the Sigma application or simply cannot download the…
url: "https://community.sigmaestimates.com/docs/troubleshooting-connection-errors/"
updated: "2019-09-11"
category: Other
---

# Troubleshooting connection errors

The Sigma application connects to remote servers when checking license (activation, keeping session alive etc.) and when checking updates.
If you are experiencing connection errors, have security software blocking internet connection for the Sigma application or simply cannot download the Sigma installation package, please whitelist the endpoints listed below.
If you do not know how or don't have access to edit security settings on your network or PC, please contact your local IT administrator instead.
 
Server 1: License and download server

Site: codegroup.dk
Ports: 80 and 443
IP: 46.36.205.18/32
Location: Denmark (Europe)

 
Server 2: Download server

Site: sigmadownload.com
Ports: 80 and 443
IP: 46.30.215.24/32
Location: Denmark (Europe)

 
Server 3: License server

Site: sigmaservice.net
Ports: 80 and 443
IP: 93.191.156.90/32
Location: Denmark (Europe)