How do I unblock my sub-domain in Let's Encrypt. I keep getting 5401

Please fill out the fields below so we can help you better. Note: you must provide your domain name to get help. Domain names for issued certificates are all made public in Certificate Transparency logs (e.g. |, so withholding your domain name here does not increase secrecy, but only makes it harder for us to provide help.

My domain is:

I am using the SSL on my Asustor NAS. it suddenly won't work or renew or unable to re-create anymore. What can I do?

Welcome @ododzilla

There is nothing wrong with Let's Encrypt. You got a cert yesterday (see here)

But, your server is not using the LE cert. It is using a self-signed Asustor cert. You can see that with a site like this SSL Checker. You need to find out why your device is not configured properly.

You might try searching this forum for 5401. Several people have reported this recently although I did not see any clear explanation of a fix. You might also try a forum for your Asus device.


Here are some links:

  1. Installing Certificate for self-hosted website on ASUSTOR NAS
  2. Unable to create certificate Nimbustor NAS, unable to apply settings 5401
  3. ASUSTOR & LetsEncrypt Renewal Failure

Hi Bruce,

Thanks for working on this. I've reviewed the first two articles. The last one is my own request for help. :wink:

Best Regards,

Greg Koss

1 Like

Teaches me to look a the original Topic Poster first before grabbing a link to it. :flushed:


@gregkoss Are you the same person as the OP of this thread, @ododzilla?



There's only one ID for me - gregkoss.

Greg Koss

This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.