As long as you’re using a secure router with a strong Wi-Fi password there’s no need to turn off your router at night or disconnect from the internet when you’re not using it, and in fact there may be good reasons not to, since your router and other devices like smart TVs and internet-of-things devices will use the quiet overnight hours to perform firmware and other important security updates. That said, it doesn’t hurt to restart your router once in a while, especially if you’re experiencing network performance problems.