PostgreSQL Logical replication FROM RDS TO EC2

Hi all;

I created a PUBLICATION in RDS and it succeeded

however if I try to create a subscrption on a PostgreSQL db that is on
an EC2 node I get an error:

prod_db=# create subscription alltables_sub connection
'host=prod-aws-endpoint.us-east-1.rds.amazonaws.com port=5432
user=prod_DBuser  dbname=prod_db' publication alltables_pub;

server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
The connection to the server was lost. Attempting reset: Failed.
The connection to the server was lost. Attempting reset: Failed.
!?>

Anyone seen this? do I need to specify the rds_admin user in the create
subscription connection line? Does aws block logical replication out of
RDS to another db?

Thanks in advance