Trying to connect Odoo 13 in production mode (reverse proxy nginx active) via external API XML-RPC and getting the following error: 

urlopen error [Errno 101] Network is unreachable

For whom came across to the same issue, I sorted this out changing odoo.conf (Odoo 13 in production mode, reverse proxy nginx active) as follows:

http_interface = 0.0.0.0
*(it was 127.0.0.1)

Using 127.0.0.1 allows only access via xml-rpc internally in the same ambient, setting url to '127.0.0.1', but with http_interface = 0.0.0.0 is possible to access externally normally setting url to ip_address.

Thanks.