Acme Challenge failure

My domains do not actively have SSL certificates, especially for the www variants. I am also haveing an issue, as every certificate I issue, is being flagged as self signed.

I tried enforcing as SSL on a subdomain and it gave this error

aiting for verification…
Challenge failed for domain
Challenge failed for domain
http-01 challenge for
http-01 challenge for
Cleaning up challenges
Some challenges have failed.

What do I do please?

where dns are managed and www version is pointed?

My DNS is managed with contabo, and the WWW version is pointed to my IP address

try to run command on terminal and try?