After Linux upgraded from 4.18.0-11-generic to 4.18.0-12-generic on my Ubuntu 18.10 network connection stopped working and on Wi-Fi settings the message: "No Wi-Fi adapter found" is shown. I can still get the connection working by selecting Linux 4.18.0-11 from the startup menu. I have ASUS Vivobook Flip 15 laptop with no Ethernet adapter available so I must get the connection working either via Wi-Fi or Bluetooth.
Ubuntu 18.04 LTS did not work for my laptop because of Wi-Fi adapter was not recognized, but Ubuntu 18.10 did work before this latest upgrade.
Network controller (apparently): Realtek Semiconductor Co., Ltd. RTL8822BE 802.11a/b/g/n/ac WiFi adapter
Solution: after disabling secure boot via Asus BIOS utility (boot options, scroll down with touchpad to the secure boot option, disable) and rebooting the Wi-Fi adapter started working.
I noticed this has already been reported as a bug here: RTL8822BE WiFi Disabled in Kernel 4.18.0-12