Move Freenas from one domain to another

We have a FeeNAS-11.3-U5. It was joined onto a domain so that we could share Windows Shares and grant permissions to those folders to AD users and groups. We need to migrate the NAS to a new domain but cannot browse to the NAS via its NETBIOS name, only it’s IP address, All of it’s DNS settings appear correct (pointing to the new DNS server) and we have added the domain name / kerberos principle etc…any thoughts…