Hola @delacal,
I think the problem isn’t the ip but the challenge used (tls-sni-01) and a combination of old software (letsencrypt-auto).
Regarding tls-sni-01 challenge, it has been disabled a month ago due to security issues and old versions of letsencrypt-auto (now its name is certbot-auto) when using apache plugin always use tls-sni-01 challenge… from version 0.21.0 it uses http-01 challenge so:
1.- You should upgrade your letsencrypt-auto version (as I said now it is certbot-auto).
2.- The upgrade is what you should do but you can also try to use the http-01 challenge with your current version:
./letsencrypt-auto certonly -a webroot -i apache -w /path/to/webroot/ -d seimem.uniovi.es,hais2018.uniovi.es
if your domains are using different webroots
./letsencrypt-auto certonly -a webroot -i apache -w /path/to/seimen-webroot/ -d seimem.uniovi.es -w /path/to/hais2018-webroot/ -d hais2018.uniovi.es
Note: I’ve removed parameter --renew-by-default you should not use it.
Un saludo,
sahsanu