What speed are you getting wired directly to the hub ?
Can you please post your network stats from the hub Open a Web browser (e.g. Internet Explorer) and enter the address http://192.168.0.1 Note: If you have enabled Modem Mode on your Hub 3.0 you will need to use 192.168.100.1 instead. Posting the stats by copy and paste will remove all personal information so no breaches. Do not login but click on where it says "Check Router Stats" and then copy and post from the following 4 tabs, Downstream, Upstream, Configuration and Network logs (if they are pasted then all personal information is * out) and we can check your power level, also while you about that can you please go around and check that all connectors to VM equipment are hand tight. Also while doing this please check for any damage to cable, or un-terminated connection without either coax or a terminator. Also please run "Check service status" at the top right of this forum and call 0800 561 0061 to check for local issues. Also one think you can do is too signup at https://www.thinkbroadband.com/broadband/monitoring/quality and setup a broadband quality monitor which will keep an eye on you connection by sending a small amout of data to the hub asking if it still on.
I dont work for VirginMedia all opinions are my own. 39 years in IT.