Unable to connect to Redshift table using db_tbl()

[dsen6644]

I can connect to my table in redshift using the following:

conn <- DBI::dbConnect(drv = RPostgres::Postgres(),
                       dbname = 'my-db-name',
                       host = 'su-dl-cluster.my-host.us-west-2.redshift.amazonaws.com',
                       port = 5439,
                       user = Sys.getenv("AWS_REDSHIFT_UID_FULL"),
                       password = Sys.getenv("AWS_REDSHIFT_PWD_FULL"))

table_df <- dplyr::tbl(conn, dbplyr::in_schema("my_schema", "my_table"))

Subbing in the credentials above, I am not able to connect to the the same table using db_tbl()

my_db_tbl <- db_tbl(table = c(schema = "my_schema", table = "my_table"),
                    dbtype = "postgres",
                    dbname = "my-db-name",
                    host = "su-dl-cluster.my-host.us-west-2.redshift.amazonaws.com",
                    port = 5439,
                    user = Sys.getenv("AWS_REDSHIFT_UID_FULL"),
                    password = Sys.getenv("AWS_REDSHIFT_PWD_FULL"))

What I get is the following error:

Error: could not connect to server: Connection timed out
	Is the server running on host "su-dl-cluster.my-host.us-west-2.redshift.amazonaws.com" (10.100.1.248) and accepting
	TCP/IP connections on port 5432?

I am unsure why the warning message would state port 5432 when I supplied 5439 as my port.