Unable to Use OAuth When Validating Org Credentials Due to a Network Issue
When creating an org credential, even if you are using valid credentials, sometimes Copado doesn't validate the OAuth authentication. This could happen if Session IP restrictions are in place.
Navigate to Setup > Session Settings and make sure that the option Lock sessions to the IP address from which they originated is not selected.
Why does Copado require this?
When using OAuth authentication to connect to an org, the login is done on your browser (using your computer's IP address) and then it passes the session Id to the connecting service (Copado). The connecting service will use the session Id to connect to the Salesforce org, and since the IP addresses are different, the connection will be dropped. This restriction will break in theory any OAuth authentication flow, it is not Copado specific.
If you have IP range restrictions at org level, make sure you add the IP addresses mentioned in the article IP Addresses.
Bear in mind that if your user has IP range restrictions at profile level, you will need to add these addresses also to your profile.