Synology Certificate renewal failed - Maximal Cert requests reached

I have synology for a while and I use let’s encrypt since 2017 I think. Two days ago, I realized my cert is expiring, so I tried to renew it manually in DSM. I have been getting different error messages as invalid domain, server cannot be reached, until yesterday night, I got the "Maximal certificate requests reached for this domain name. Was it too many requests going out from synology, but response never made it back? I have no idea.

There was no change on my home network, routers or router settings. My port forwarding settings did not change. I can still access my synology from outside.

My domain is:

I ran this command:
Manual certificate renewal (or added new, renew with let’sencrypt)

It produced this output:

My web server is (include version):

The operating system my web server runs on is (include version):
Synology DSM

I can login to a root shell on my machine (yes or no, or I don’t know):

I’m using a control panel to manage my site (no, or provide the name and version of the control panel):
DSM 6.2.2-24922 Update 4

The version of my client is (e.g. output of certbot --version or certbot-auto --version if you’re using Certbot): N/A

1 Like

Hi @JonesCZ

checking there is no certificate created. Rechecked with Google to see if my tool is buggy - the same result, no new certificate.

So the error message may be "not ideal":

There is a Failed Validation limit of 5 failures per account, per hostname, per hour.

That's your limit. One hour later, it's gone.

But the url check says: Your http doesn't answer -> so you can't create a certificate via http validation.

No, only https works. But http is required.

Did you change your ISP? Some ISP block port 80. If not: Firewall, wrong router ....


Thank you for prompt response. I will check with my ISP (did not change) and verify port forwarding on 80. I will get back to you with my findings.


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