Putting your router by a radiator will almost certainly affect its range and speed. A radiator is a big metal sheet which is exactly what reflects WiFi radio signals.
I am NOT a Sky Employee Myself & Others offer our time to help others, please be respectful.
Also worth considering it's unwise to subject microelectronic equipment to significant temperature variation, and water is a very good absorber of microwave energy.
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Sky Glass 55" (on ethernet) & two Stream Pucks (one ethernet / one WiFi) BT Halo 3+ Ultrafast FTTP (500Mbs), BT Smart Hub 2
