Re: Vivid 100 upload speed - 150KB/s when backing up to cloud ...
machine plugged into hub you say - is that with the hub in modem mode - if not just do a test like that
log into hub3 - 192.168.0.1 [or 192.168.100.1 if in modem mode] - DON'T SIGN IN, click - click router status [centre of screen] - and post the downstream and upstream figures - to see those press on the grey buttons/boxes labeled - upstream - downstream
So your 150 KB/s is actually 1.2Mb/s. Still a lot less than the 4.5Mb/s that speedtest tells you, but not as bad as your title suggests.
You know that the VM modem and circuit is capable of 4.5 Mb/s uplink and you should be able to get that speed. I think you need to investigate locally why you can't get that much data into the Hub from your PC.
Is the backup PC performing compression and de-duplication on your files? That could explain the lower speed.