In the status bar of your Huawei P20 Pro, see that the W-Lan and mobile data are active simultaneously, then you may wonder why this is so.
The reason you can see the W-Lan and mobile data icons in the status bar at the same time is as follows:
In the Android system settings of the Huawei P20 Pro there is the option "Mobile data always on". If this option is active, the mobile data connection remains active even if the smartphone is connected via W-Lan.
If you want to deactivate this double Internet connection on the Huawei P20 Pro, for example for the simple reason that more battery power is used, you can do this as follows:
Deactivate mobile data "Always on" on the Huawei P20 Pro
Open the settings of your Huawei P20 Pro
Go to "Wireless & Networks" and then to "Mobile Network"
Scroll down to "Advanced" and select the entry
Now deactivate the option "Mobile data always activated" If you are now in a W-Lan network, the mobile data will be deactivated automatically.
If you switch off the W-Lan on the Huawei P20 Pro, the mobile data will be activated again.