The default bandwidth setting is "unlimited". If you would like to throttle it back so that the backup process does not try to utilize the full bandwidth available to the client, you can modify the bandwidth limit under the user profile. This can be done through the reseller portal when managing a user, or the user can do this themselves through modifying their user profile.
Currently your throttle options are:
> 64Mbps
> 32Mbps
> 16Mbps
> 8Mbps
> 4Mbps
> 2Mbps
> 1Mbps
> 512Kbps
> 256Kbps
> 128Kbps
> 64Kbps
