Expiring certificate despite automatically renewing

Today I got the information, that my certificate will expire in 20 days. I am confused because since the beginning in 2020 it had been automatical renewed. I never got a notice by Let's Encrypt indicating malfunction occurs.
What should I do now?

Hi @Sascha1

please read the complete mail and the link shared in the mail, not only a small part.

The link about mails has the complete solution.

Hallo Sascha1,
auf DSM anmelden->Systemsteuerung->Sicherheit->Zertifikat->HinzufĂĽgen->Zertifikat erneuern

Welcome to the Let's Encrypt Community :slightly_smiling_face:

To supplement @JuergenAuer's recommendation:

@Woelli

Welcome to the Let's Encrypt Community, Joachim :slightly_smiling_face:

Do you know @Sascha1? I didn't see anything in @Sascha1's post mentioning a Synology NAS, so I thought maybe I missed another post from @Sascha1 somewhere.