Action is required to prevent your Let’s Encrypt certificate renewals from breaking.
Your Let’s Encrypt client used ACME TLS-SNI-01 domain validation to issue a certificate in the past 60 days.
"TLS-SNI-01 validation is reaching end-of-life and will stop working on February 13th, 2019.
You need to update your ACME client to use an alternative validation method (HTTP-01, DNS-01 or TLS-ALPN-01) before this date or your certificate renewals will break and existing certificates will start to expire.
If you need help updating your ACME client, please open a new topic in the Help category of the Let’s Encrypt community forum:
My domain is: https://geometricfigure.com
I ran this command: na
It produced this output: na
My web server is (include version): nginx 8
The operating system my web server runs on is (include version): Ubuntu 16.04
My hosting provider, if applicable, is: Digital Ocean
I can login to a root shell on my machine (yes or no, or I don’t know): yes!
I’m using a control panel to manage my site (no, or provide the name and version of the control panel): no