Ubuntu 16.04升级后WiFi连接选项消失问题求助

Hey there, let's work through this WiFi issue together—since you're new to Ubuntu 16.04, we'll take it step by step to get your wireless back up and running.

First, Confirm Your Wireless Hardware Type #

You mentioned running lspci -vnn | grep Net didn't return the expected results. That's a clue: your WiFi adapter might be a USB device (instead of a PCI card, which is what lspci checks). Let's verify that:

• Open a terminal and run this command: lsusb
• Look for entries labeled with "Wireless", "WiFi", or a brand name like Broadcom, Realtek, or Intel. Note down the hardware ID (it’ll look something like 1234:5678)—this will help us track down the right driver later.

Check if Your Adapter is Blocked #

Sometimes wireless adapters get blocked by software or hardware switches without you noticing:

• Run rfkill list in the terminal. If you see "Soft blocked: yes" next to your wireless device, unblock it with: sudo rfkill unblock all
• Double-check your laptop for a physical WiFi toggle button, or a function key combo (like Fn+F2) that might have turned off WiFi accidentally.

Install Drivers Manually (Even if Additional Drivers Shows Nothing) #

The "Additional Drivers" tool doesn’t always detect every driver, especially after an upgrade. Let’s install common Broadcom drivers manually—just make sure you have an internet connection first (use Ethernet or USB tethering from your phone):

1. Update your package list: sudo apt update
2. Try installing the Broadcom STA driver first (this works for most modern Broadcom chipsets): sudo apt install bcmwl-kernel-source
3. If that package isn’t available, try the open-source alternative for older chipsets: sudo apt install firmware-b43-installer
4. Reboot your system after installation, then check if the WiFi connection option reappears.

Fix Network Manager Glitches #

Upgrades can sometimes mess up Network Manager settings. Let’s reset it:

• First, restart Network Manager to rule out a temporary glitch: sudo service network-manager restart
• If that doesn’t work, reset your saved connections (we’ll back them up first to be safe):
  1. Create a backup folder: mkdir ~/network-connection-backups
  2. Copy your existing connections: sudo cp /etc/NetworkManager/system-connections/* ~/network-connection-backups/
  3. Delete the current connection files: sudo rm -rf /etc/NetworkManager/system-connections/*
  4. Restart Network Manager again: sudo service network-manager restart
  5. Now you can re-add your WiFi connection through the "Edit Connections..." menu.

Dig Into System Logs for Clues #

If none of the above works, let’s check the system logs to find what’s going wrong:

• Run dmesg | grep -i wireless or dmesg | grep -i wlan to see error messages related to your wireless hardware.
• If you share the output of these commands, we can pinpoint the exact issue more easily.

内容的提问来源于stack exchange，提问作者user1893354