Ttgjyuk

Just installed Ubuntu on new HP desktop "pavillion"all in one.
Dual boot set up. I get the message no wifi adapter found when attempting to get online.
What to do? Oh I do not know how to copy and paste my terminal info so it actually looks like it does on the terminal. (A little help with that would stop annoying people that are reading my questions.)

When I enter sudo lshw -C network I get:

*-network 
description: Ethernet interface
product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
vendor: Realtek Semiconductor Co., Ltd.
physical id: 0
bus info: pci@0000:01:00.0
logical name: enp1s0
version: 15
serial: c8:d9:d2:7b:00:b3
size: 1Gbit/s
capacity: 1Gbit/s
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress msix bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full firmware=rtl8168h-2_0.0.2 02/26/15 ip=10.0.0.223 latency=0 link=yes multicast=yes port=MII speed=1Gbit/s
resources: irq:49 ioport:f000(size=256) memory:fea04000-fea04fff memory:fea00000-fea03fff
*-network UNCLAIMED
description: Network controller
product: Realtek Semiconductor Co., Ltd.
vendor: Realtek Semiconductor Co., Ltd.
physical id: 0
bus info: pci@0000:02:00.0
version: 00
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress cap_list
configuration: latency=0
resources: ioport:e000(size=256) memory:fe900000-fe90ffff

So I followed the already answered question advice of making sure I had the correct kernel which is currently 4.15 and I have the most updated rtl8822befw.bin firmware installed and I still am getting the no wifi adapter prompt. I do not know all the commands that I could be using to get this solved. The adapter is found and operational in windows and the Ethernet cable allows me to get online for Ubuntu.

When I enter lspci -nnk | grep -A2 0280 I get:

02:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd. Device [10ec:b822]
 Subsystem: Hewlett-Packard Company Device [103c:831b]
 Kernel modules: r8822be

When I enter rfkill list I get:

0: hci0: Bluetooth 
 Soft blocked: no 
 Hard blocked: no 

Any other Ideas ?

I was having the same issue on a Lenovo Legion Y530 laptop, which has a Realtek rtl8822be wireless network card, with 18.10 Ubuntu Mate.
What I did to fix it was, plugging it into the network via ethernet, I ran sudo apt-get update and sudo apt-get upgrage then, using your favorite text editor edit blacklist.conf

sudo gedit /etc/modprobe.d/blacklist.conf

I added the line:

blacklist ideapad_laptop

then saved and closed the file, and rebooted.

if you didnt want to make this change, without testing it, you could do this:

sudo rmmod ideapad_laptop

doing this, gave me instant results. wireless networks appeared, I was able to connect, and life was great again. I have no idea if your setup will have an ideapad module, but you might try it. Alternatively, you might have an HP module that needs blocking to enable this device.