Should be ok although speeds will be attenuated somewhat - but that shouldnt matter too much.
One thing you could do is get a 20-50m run of Cat5e/6 cable for <£10 and run it to the Hub and test the connection.
If it works just leave it connected until the powerlines are working. The circuits must be the same or go through the same consumer unit/fuse box (most upstairs/downstairs ring mains do) and be free of any "noise". Dont use socket extenders - go straight into the plug sockets
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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 2 WiFi,) SH2 in modem mode with Airport Extreme Router +2 Airport Express's. On VIVID200, Talk Anytime Phone, x2 Mobile SIM only iPhones.