> For the complete documentation index, see [llms.txt](https://knowledge.illumina.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://knowledge.illumina.com/instrumentation/novaseq-6000/instrumentation-novaseq-6000-troubleshooting-list/000001858.md).
# Troubleshooting CE or Z:\ drive not connecting on the NovaSeq 6000
**Background** The NovaSeq 6000 includes two computer systems, the Control Computer (SBC) and the Compute Engine (CE). The CE is a Linux-based computer that is mapped to the Z:\ drive and stores .cbcl data prior to copying to the network drive. The CE is also responsible for Real Time Analysis (RTA) processes including image analysis and base calling. For the Control Computer to connect to the CE, it must be mapped to the Z:\ drive properly.
The CE (Z:\ drive) may fail to mount if the drive is mistakenly unmounted, or in rare instances, if the CE drive becomes non-functional.
**Troubleshooting Actions**
**Remounting the CE (Z:) drive**
* Open NovaSeq Control Software (NVCS)/NovaSeq Service Software (NVSS).
* If the Z:\ drive is disconnected but the drive is still mounted, open NVCS/NVSS.
* When the CE turns on, the status of the Z:\ drive changes to green.
* Once the CE connects and the Z:\ drive status turns green, power cycle the system. For more information on power cycle, see Knowledge Base article [How to Power Cycle the NovaSeq 6000 System](https://github.com/illumina-swi/illumina-knowledge/tree/master/articles/Knowledge/How-to-Power-Cycle-the-NovaSeq-6000-System/README.md).
**Note**: If the system is powered on too quickly with less than 30 seconds between toggling the switch at the back and pressing power button at the side, the boards may fail to come online in the correct order and the system may fail to initialize. To avoid this issue, perform a 'slow' reboot by waiting at least 2 to 5 minutes between toggling the power switch at the back to ON and pressing the power button on the side to boot up the system.
* If the issue persists, see *Re-mapping the CE using Network Discovery* and *Check Windows Defender Settings* sections below.
**Re-mapping the CE using Network Discovery**
1. Close NovaSeq Control Software (NVCS).
2. If an internal network location is mapped to the Z:\ drive, disconnect the network location using the following steps.
1. Open File Explorer and select **This PC** on the left.
2. Right-click on the network location, and select **Disconnect**.
3. Confirm that the network location is no longer mapped to the Z:\ drive
3. Open the Windows Control Panel and select **Network and Sharing Center**.
4. Choose **Change advanced sharing settings** from the top-left corner.
5. From there, select the **Guest or Public** dropdown menu and turn Network Discovery **ON** (Figure 1)
6. Open File Explorer, right-click on **This PC** in the left panel, and select **Map network drive**.
7. In the **Drive** dropdown menu, ensure that the Z: drive is selected.
8. The **Folder** dropdown menu should have the CE computer listed from previous connections (Figure 2).
* This will have an IPv6 address similar to \fddc:65e5:66fa::1\ilmn
9. Select **Finish** to complete the mapping process.
10. In the File Explorer application, navigate to **This PC** and confirm that the CE computer is accessible through the Z:\ drive.
11. Turn Network Discovery OFF by following **Steps 3-5** and selecting **OFF** for Network Discovery.
12. Launch NVCS.
**Figure 1:** Screenshot of selecting 'Guest or Public' and turning Network Discovery to ON.
**Figure 2:** Mapping the Z:\ drive using the IPv6 address.
**Check Windows Defender Settings**
* Open Control Panel, then select All Control Panel Items > Windows Firewall > Allowed Apps
* All instances of *Instrument Shell* and *Voyager.Simulator* should be allowed for Domain, Private, and Public for all instances of the instrument shell.
* Select **OK** to save the Windows Firewall settings.
* Close the Control Panel and relaunch the Novaseq 6000 Control Software
If the issue persists after the power cycle, checking Windows Defender settings and remounting, contact [Illumina Technical Support](https://www.illumina.com/company/contact-us.html#/united-states/technical-support) for the next steps.
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| *For any feedback or questions regarding this article (Illumina Knowledge Article #1858), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000002470%20-%20Instrumentation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |
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