Go to Settings → Request Portal → Operational Hours.

Once you enable the setting, you will be able to set timings for your portal. You can enter the opening and closing times. There is an option to make certain days closed for operations.

You can edit the closing and opening times in this way:

Next, you can set certain restrictions from the following options:

After setting the operational hours, click Update.

The following error will show up if you have selected the option 'Restrict users from using the portal outside of operational hours' :

Setting Operational Hours in Request Portal