When rsync stalls as well after couple of seconds when initially running fine I ended up with the following brute force solution to start and stop an re-start the download every 60s:
cat run_me.sh
#!/bin/bash
while [ 1 ]
do
rsync --partial --progress --rsh=ssh user@host:/path/file.tgz file.tgz &
TASK_PID=$!
sleep 60
kill $TASK_PID
sleep 2
done