I can't do this either. And I'm an author of router code in the '90's so what article are you reading that said you can use WiFi and your mobile data connection at the same time?
I have a in-house development network using wi-fi and hardline without any internet. Im trying to connect my Galaxy S5 (6.0.1) to my network so I can use the shared network printer. However, my phone assumes a net connection whenever I turn on my wi-fi, therefore I can access my network but cannot simultaniously use mobile data. Even if my Smart Network switch is turned on. Any ideas or suggestions. I mean seriously, WI-FI is NOT a internet connection by default, but mearly a wireless network. Why is this so difficult?

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