# MDM - Unable to Reach GCM

## Problem

You are trying to scan a managed android device and you get the error message "Unable to Reach GCM"

## Cause

This could happen, due to one of the following reasons:

- [Proxy Not Configured / Proxy Authentication Failed](https://www.manageengine.com/products/desktop-central/mdm-unable-to-reach-gcm.html#proxy)
- [Port Blocked](https://www.manageengine.com/products/desktop-central/mdm-unable-to-reach-gcm.html#port)

## Resolution

### Proxy Not Configured / Proxy Authentication Failed

Endpoint Central needs to reach the GCM server thorough the internet. If Proxy settings has not been configured or the Proxy authentication fails, Endpoint Central server will not be able to reach the GCM. So, ensure that the Proxy settings are configured correctly.

### Port Blocked

Ensure that port # 443 is open on the firewall, for Endpoint Central server to reach the GCM.

**Applies to:** Proxy, Device Scanning

**Keywords:** GCM, Enrollment failure, Device Scanning

## Unable to resolve this issue?

If you feel this KB article is incomplete or does not contain the information required to help you resolve your issue, upload the required [logs](https://www.manageengine.com/products/desktop-central/logs-how-to.html).

## Other KB articles

| Other KB articles |  |
|---|---|
| - [Agent Installation](https://www.manageengine.com/products/desktop-central/knowledge-base.html#agent-installation)<br>- [Configurations](https://www.manageengine.com/products/desktop-central/knowledge-base.html#windows-configurations)<br>- [Inventory Management](https://www.manageengine.com/products/desktop-central/knowledge-base.html#inventory-management)<br>- [Patch Management](https://www.manageengine.com/products/desktop-central/knowledge-base.html#patch-management)<br>- [Software Distribution](https://www.manageengine.com/products/desktop-central/knowledge-base.html#software-distribution)<br>- [Service Pack Installation](https://www.manageengine.com/products/desktop-central/knowledge-base.html#service-pack-installation)<br>- [Desktop Sharing](https://www.manageengine.com/products/desktop-central/knowledge-base.html#remote-desktop-sharing)<br>- [Active Directory Reports](https://www.manageengine.com/products/desktop-central/knowledge-base.html#active-directory-reports)<br>- [User Logon Reports](https://www.manageengine.com/products/desktop-central/knowledge-base.html#user-logon-reports)<br>- [Endpoint Central SP Upgrade](https://www.manageengine.com/products/desktop-central/knowledge-base.html#service-pack-upgrade)<br>- [Miscellaneous](https://www.manageengine.com/products/desktop-central/knowledge-base.html#miscellaneous)<br><br>[» More](https://www.manageengine.com/products/desktop-central/knowledge-base.html) |  |

[Mobile Device Management - Knowledge Base](https://www.manageengine.com/products/desktop-central/knowledge-base.html#mobile-device-management)