As per the chosen answer here I needed to configure security on the producer for the connector that Kafka Connect is running. So I added these lines to kafka-connect settings;
CONNECT_PRODUCER_SECURITY_PROTOCOL: SASL_PLAINTEXT
CONNECT_PRODUCER_SASL_MECHANISM: PLAIN
CONNECT_PRODUCER_SASL_JAAS_CONFIG: org.apache.kafka.common.security.plain.PlainLoginModule required username="admin" password="admin-secret" user_admin="admin-secret";
Right now the data is being transfered from the old Kafka setup to new one.