Why is my WiFi disabled in Ubuntu?

I'm using ubuntu 18.04, and sometimes wifi will be disabled and display a blank page in network settings. I've tried

$ ping 8.8.8.8
connect: Network is unreachable

and

$ nmcli device
DEVICE TYPE STATE CONNECTION
wlp3s0 wifi unavailable -- 

and

$ sudo lshw -class network
*-network description: Ethernet interface product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 . . .
*-network DISABLED description: Wireless interface product: QCA9377 802.11ac Wireless Network Adapter vendor: Qualcomm Atheros physical id: 0 . . .

and

$ sudo iwconfig wlp3s0
wlp3s0 IEEE 802.11 ESSID:off/any Mode:Managed Access Point: Not-Associated Tx-Power=20 dBm Retry short limit:7 RTS thr:off Fragment thr:off Encryption key:off Power Management:on

and

$ rfkill list all
1: phy0: Wireless LAN Soft blocked: no Hard blocked: no
3: hci0: Bluetooth Soft blocked: yes Hard blocked: no

I'm trying to reinstall fireware-realtek and several other drivers manually:

$ sudo modprobe -r rtl8723de && sudo modprobe rtl8723de

But nothing changes. When I run a wlp3s0 scan...

$ sudo iwlist wlp3s0 scan | grep ESSID

I get the following:

 wlp3s0 Interface doesn't support scanning: Network is down

So I try to turn it on...

$ sudo systemctl stop NetworkManager
$ sudo ip link set wlp3s0 up

And get the error:

RTNETLINK answers: Input/output error

So the only way that I can access the wifi is reboot.

2 Answers

Had this problem today after updating a week or so ago then putting my laptop away for a while.

Pulled out my laptop and wifi wasn't working. Same outputs for the same commands.

If you run the software updater again it should fix your problem (which is annoying if you only have wifi).

If you can, connect to ethernet to get this done. If not, plug your phone into your pc and enable USB tethering (if your phone has the option).

Running the software updater whilst connected via USB tethering fixed this problem for me.

It seems the last update invalidated the drivers for the wifi cards? I'm not sure.

I had the same problem and I read infinite Answer and questions. But the solution is very very easy, if you really are experimenting a WiFi networking hard blocking.

Here the solution:

1. First check with

   sudo lshw -class network 

   a response like that (may changes but it is important that you see the wi-fi adpater):

   *-network DISABLED description: Wireless interface product: QCA9377 802.11ac Wireless Network Adapter vendor: Qualcomm Atheros physical id: 0

2. Turn off your laptop and remove physically the battery pack.

3. After a while reinsert the battery and the power supply. When you enter in Ubuntu again in network settings you can see that is possible to set your WiFi.