My domain is: *.inuvem.org
I ran this command: synology control panel
It produced this output: "Failed to connect to the Let's Encrypt server. Check the server address and your network settings."
My web server is (include version):
The operating system my web server runs on is (include version): DSM 7.1.1-42962 Update 2
Is outgoing https working at all from your synology box? Can you use a command line to check?
Sorry, I'm a little newbie 
Test a port using a command
$ telnet portquiz.takao-tech.com 443 Trying ... Connected to XXXXX
$ nc -v XXXXXX 443 Connection to XXXXXXXX 443 port [tcp/daytime] succeeded!
$ curl XXXXXXXX:443 Port 443 test successful! Your IP: XXXXXXXX
$ wget -qO- XXXXXXXX:443 Port 443 test successful! Your IP: XXXXXXX
Cool, so how about curl https://acme-v02.api.letsencrypt.org/directory?
Using Let's Debug (see here) to test connections to your server shows you have an AAAA record in the DNS for a private IP. You should change that to a public IP or remove the AAAA record to use only IPv4.
I don't know that this is causing your original problem but the error message is not very informative. It is something you need to fix to get an LE cert in any case.
EDIT: Also, your DNS config has some problems you should address. See dnsviz report