Remove everything but first 'source-directory' line in /etc/network/interfaces
.
Using nano:
sudo nano /etc/network/interfaces
Use CTRL+K to delete lines, CTRL+O to save, and CTRL+X to exit nano editor.
Enable 'dhcpcd' with:
sudo systemctl enable dhcpcd
sudo systemctl disable networking
Restart the Pi to have the changes take effect.
Reboot from GUI, or use terminal command:
sudo reboot
WiFi should work now.
Is any chance to run RTL8211 wifi dongle with Raspberry Pi model B+ ?
Non of https://github.com/fastoe/RTL8811CU_for_Raspbian or https://github.com/morrownr/8821cu-20210118 helped