The LiveCD image connects to wifi, but the installed operating system cannot. What could be the problem?

Question

linux

I got an old netbook from Samsung. I downloaded the LiveCD image of Xubuntu, checked how it runs, connected to the wifi distributed from my laptop, visited Google and Yandex. Everything is fine and working.
I installed an operating system from the same flash drive, everything works, but besides, wifi cannot connect. I checked the options, didn't help. I loaded the LiveCD image again and tested wifi, it connected and web pages open without problems.
What could be the problem?

Answer 1

Put Xubuntu 15.04 the problem was solved by itself. Campaign in the firewood was the case.

Answer 2

What is "besides, wifi can not connect"? Is the connection established with the access point? Are packages being sent? Are packages accepted? DHCP does not give an address? What's in dmesg and other logs about this?
What kind of waffle adapter? Is the driver proprietary or open source?

Answer 3

In wood? What options were tested? What version of Ubuntu? There is no ubuntu at hand, so I can underwrite some point.
In the terminal we do:
lspciit will give out all devices. Find network (Ethernet) devices there and see what they write about them. (example

02:00.5 Ethernet controller: JMicron Technology Corp. JMC250 PCI Express Gigabit Ethernet Controller (rev 03)

)
ifconfig -a will show all available connections. Among them there should be something about wlan
uname -awill give a brief information on ubuntu.
At first attentively we read this link
We write here result of researches.