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
Is there some standard documentation you guys provide for this issue ?
My web server is (include version):
Go http web server in std lib
The operating system my web server runs on is (include version):
Centos 7.6
My hosting provider, if applicable, is:
Rackspace
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
I don’t know of any (a wiki would be nice).
But checking your domain, I can see that port 80 doesn’t reach your server.
If your ISP blocks port 80 then HTTP-01 is not an option for you.
Otherwise, you will need to ensure the Internet can reach your server over TCP port 80.
OR use DNS-01 validation method.
Not as “simple” but if your DNS service provider is supported, you can use a DNS plugin to automate the renewals.