My Cloud PR4100 / EX2 Ultra Login My Cloud OS5 504 Error

A 504 Gateway Timeout error while logging into a WD My Cloud PR4100 or My Cloud EX2 Ultra running My Cloud OS 5 usually means the NAS web server cannot get a response from one of its internal services in time. This can be caused by a temporary service issue, a hung process, database corruption, or a firmware problem.

Common causes

NAS services are stuck or overloaded.

Firmware upgrade did not complete correctly.

Cloud or authentication service is not responding.

Browser cache or HTTPS redirect issues.

System database or web interface has become unresponsive.

How to fix the My Cloud OS 5 504 Error

Restart the NAS

Power off the PR4100/EX2 Ultra.

Wait 30 seconds.

Turn it back on and wait until the LED is solid blue.

Access the NAS using its IP address

Instead of using:

http://mycloudpr4100

http://mycloudex2ultra

Try:

http://<NAS-IP-address>

or https://<NAS-IP-address>

WD also recommends ensuring your PC is on the same network and not connected through a VPN or different VLAN.

Try another browser

Chrome

Firefox

Edge

Private/Incognito mode

Clear browser cache and cookies.

Check NAS resource usage

If SSH is enabled, verify whether CPU or memory is maxed out by antivirus scans, indexing, or other services.

Perform a 4-second pin reset

This resets the administrator password without deleting your data and can resolve some login issues after OS 5 upgrades.

Perform a 40-second pin reset (if necessary)

If the dashboard never loads, WD recommends a 40-second pin reset to restore the web interface while preserving data when possible.

Check for service outages

There have been previous My Cloud OS5 login outages that prevented users from signing in even though their devices were working normally. Before performing major troubleshooting, verify the current service status.

If the problem continues

If you can still access your files via SMB (\\NAS-IP\Share) but the Dashboard returns a 504 error, the issue is likely with the web interface or internal services rather than your data. In that case:

Back up important data if possible.

Collect system logs.

Contact WD Support if a reset does not resolve the issue.

As a last resort, perform a System Only Restore or reinstall the firmware, which preserves user data but reinstalls the operating system.

If you can tell me:

Model: PR4100 or EX2 Ultra

Firmware version (for example, 5.27.161)

Whether the 504 error appears locally (using the NAS IP) or only through remote access

I can provide more specific troubleshooting steps.