Buffalo Terastation

[wes1993]

Hello,
i'm trying to create an SSL certificate for my Buffalo Terastation using this command:

DUCKDNS_TOKEN=redacted \
lego --accept-tos --email redacted --dns duckdns --domains domain.com run

I have inserted all te correct info but when i try to import the certificate in my Terastation i have an error....
There is a guide on how generate the certificate in the Buffalo website using Let's Encrypt:
https://www.buffalotech.com/knowledge-base/secure-your-terastation-by-installing-free-ssl-certificates-from-lets-encry

So i don't know why won't work, i hope someone reading the Buffalo manual can tell me the differences between the LEGO generated certificate and the procedure in the Buffalo website.

Best Regards
Stefano