I am new to Ubuntu and Linux. I replaced Windows with Ubuntu 18.04 on my HP laptop, with WiFi chip RTL8723DE.
I have already fixed a problem with an error saying "WiFi adapter not found". I followed this answer and this answer to solve that problem.
Now I can interact with WiFi, but after rebooting the PC, even though I can scan and see WiFi networks, when I try to connect, I get the error: activation of network connection failed
I am a novice using Ubuntu/Linux and I don't have Windows anymore. Please help me find a solution or help direct me to resources. I don't know where to start searching.