Let's encrypt certificate on Synology NAS

Hello everyone,

I’m trying to get a signed certificate for my synology NAS. I’ve created a domain name using the synology DDNS service and with that domain name I added a certificate with the “get certificate from let’s encrypt” option. It created the certificate and it is now my default certificate on the server. However, chrome is still telling me the certificate is invalid. Did I miss a step somewhere? I looked around on the forum and that is how I got this far in the first place, but I might have still missed something. Please let me know if you need more information from me or if you have a solution to my problem.

With kind regards,


Chrome has a tendency to cache certificates for a bit. So even if you hard-refresh a tab after the server starts hosting a new cert, it will still show as the old one. Try closing out Chrome completely and then going back to the site. You could also try a different browser to verify.

I have tried to do this but unfortunately that didn’t help.


The DDNS service also reports everything is fine

OK I’m pretty sure it’s a faulty DDNS

Hi @Stroopwafelandcoffee

it's impossible to check your domain, because there are only timeouts.

Your new certificate is visible

CRT-Id	Issuer	not before	not after	Domain names	LE-Duplicate
	CN=Let's Encrypt Authority X3, O=Let's Encrypt, C=US
	2019-03-25 14:38:35
	2019-06-23 13:38:35
	no duplicate

but I can't check if your server uses that or if there are additional problems.

Yes I am puzzled as to why the DDNS does not function properly, but that is on Synology’s end and not your problem. I’ll get back to this if necessary.

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