I have 3-phase wiring at my hometown and using HomePlug to connect PCs/laptops located far from the router.

On the same phase, you can expect optimal performance but degrades slightly as the wire length goes further (e.g. between downstairs & upstairs).

On different phase, it still work but with some degradation in performance. However, if your Internet access is 50Mbps or below, it should not be an issue. It should not also be an issue for HyppTV.