Slow transfert rate for some jobs

Hi,

Some of our backup jobs are slow, i noticed that the network bandwidht is not used (only about 10%). Please take a look at 3 screenshot. It seems BE is limiting bandwidht ? How can i force it to use more.

On the print screen you can clearly see that BE uses only few bandwidht, the LAN speed test is very good (so it's not the network and not the strorage)

Note that we have others jobs are running at more than 5000 MB/min and i noticed that the network is then used at more than 80% (witch is very good).

Please help