AWS RDS DB Migration

I have a PostgresFB on an AWS RDS instance that we want to migrate to an on-site server. The problem we having is the migrating of data and the time it is taking to migrate the data. I have tried AWS migration and that is taking an hour to do 100mb just imagine the time if it is as 80GB DB. If I do a backup and compress I can get the DB down to 47GB and then using AWS Data sync and that is only transfer it at 1mb a second so going to take quite a while to transfer. What other suggestions is there for me to get this db either sync faster or get the data out of AWS faster? Any suggestions from experience?