Yes, it is possible to turn off WiFi only on the (tp-link) router during nighttime.
Yes, it is possible to turn off WiFi only on the (tp-link) router during nighttime.
You might want to explore IFTTT or similar platforms. If your router is covered by a service, it could be as easy as IF: Time equals xx:xx THEN: Disable Wi-Fi. It's a small chance but worth investigating.
With the latest firmware installed, you can configure time schedules via the Access Control > Schedules menu. Assign these schedules to specific device MAC addresses as required. For more details, check the Emulators page on TP-Link's site: https://www.tp-link.com/us/support/emulator/