At least one repeater is in use on the Wi-Fi network.
Take the Wi-Fi repeater out of operation temporarily so that the cooktop and the ventilation hood are physically connected to the same radio cell.
If taking the Wi-Fi repeater out of operation temporarily solves the problem, check if the Wi-Fi repeater can be configured with its own Wi-Fi network (SSID). Then connect the cooktop and the ventilation hood to your Wi-Fi network (SSID).
Alternatively, you can attempt troubleshooting as follows:
Despite logging on successfully, Con@ctivity is inoperative
The ventilation hood does not switch on until several minutes after the cooktop has been switched on