ERROR 2005 Cannot connect with JDBC using URL with /schema or :port/schema at the end (1 reply)

I have a weird circumstance that just popped up. The same application on two different servers at AWS--one can connect to it's server with URL jdbc:mysql://hostname:port/schema; and when run on an identical environment in another AWS account, cannot to its RDS using that same format, but can if I drop the port and schema.

Has anyone seen this error before?

Thanks,
Benjamin