Hi there,
No, you can use the range even if you are connected to the WiFi.
Connecting the range to the WiFi enables you to monitor, change settings, and even remotely command the range to "start pre-heating," as an example.
Please see pages 34 - 35 under the "Using the smart control feature" section of the manual for more details.
Manual
https://downloadcenter.samsung.com/content/UM/202103/20210308172014230/NE63A6111_AA_01_EN.pdf
Have a great day.
^Charles