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I am new to Ubuntu and have never written a question. I have just downloaded 18.04. I can connect to the internet with a cable but I am not able to do so wirelessly. Please, I have read several answers, but if I'm told to ping a number or enter a list of instructions I need to know where to enter them. I cannot use 'connect to hidden wireless network' because this does not appear in the menu at all. Any help would be greatly appreciated.
When I ping it say Network is unreachable. My network controller is Realtek Semiconductor Co., Ltd. Device d723.
Network controller : Realtek Semiconductor Co., Ltd. Device [10ec:d723] Subsystem: Hewlett-Packard Company Device [103c:8319]