Error adding data source PostgreSQL DB to Jasper Reports Server

I'm trying to add a new data source in Jasper Reports Server community edition but I'm getting a vague error, I'm sure of my credintials and my data connection settings,

There was an error on the server. Try again or contact site administrators.

When searching about this issue most answers suggest it's a security issue but I'm connecting it to PgAdmin and it works fine.

This PostgreSQL DB is running in a docker container and I'm using windows OS

Any ideas would be very appreciated.

Thanks a lot.