Why?
You can do that - but the Hub has been designed to be left on 24/7 with no issues. A lot of VM updates/firmware changes are pushed out overnight and so are all installed and settled at that time - rather in the first 15' of so after switching on in the morning - if you are in a hurry to get connected it might be an issue. Also, you will lose connectivity to devices that might need a permanent connection - cameras, doorbells, TV recorders, etc.
Conventional wisdom also says that the point turning on/off any electronic equipment is always the operation likely to cause a problem with it - but the chances of any problems occurring are still very low.
So you need to make the call.
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John
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I do not work for VM. My services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired, 1 WiFi, 1 on PA) Hub5 in modem mode with Apple Airport Extreme Router +2 Airport Express's. On 250Mbps, Talk Anytime Phone, x2 Mobile SIM only iPhones.