raspberry pi 3 + monitor mode isn't available.

[ghost]

I'm a newbie to linux. I'm trying to install AWUS036ACH to my Raspberry pi 4.14.34-v7+
i run these commands

$ sudo apt update
$ sudo apt upgrade
$ sudo apt --purge autoremove
$ sudo reboot
$ sudo apt install raspberrypi-kernel-headers
$ sudo wget https://raw.githubusercontent.com/notro/rpi-source/master/rpi-source -O /usr/bin/rpi-source && sudo chmod +x /usr/bin/rpi-source && /usr/bin/rpi-source -q --tag-update
$ sudo apt-get install bc git -y
$ git clone https://github.com/astsam/rtl8812au
$ cd rtl8812au
$ sed -i -e 's/CONFIG_PLATFORM_I386_PC = y/CONFIG_PLATFORM_I386_PC = n/g' Makefile
$ sed -i -e 's/CONFIG_PLATFORM_ARM_RPI = n/CONFIG_PLATFORM_ARM_RPI = y/g' Makefile
$ make
$ sudo insmod 8812au.ko
$ sudo cp 8812au.ko /lib/modules/$(uname -r)/kernel/drivers/net/wireless
$ sudo depmod
$ sudo reboot

when i run iwconfig

wlan0 unassociated Nickname:"WIFI@REALTEK"
Mode:Auto Frequency=2.412 GHz Access Point: Not-Associated
Sensitivity:0/0
Retry:off RTS thr:off Fragment thr:off
Encryption key:off
Power Management:off
Link Quality:0 Signal level:0 Noise level:0
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0

when i give commands

$ ip link set wlan0 down
$ iwconfig wlan0 mode monitor //doesn't give me any errors
$ ip link set wlan0 up

i checked if i could do packet injections with

$ aireplay-ng -9 wlan0
it isn't successful. Have you got any suggestions? Thanks

[MrDrache333]

Exactly the Same here :(

[ghost]

Try this:

$ sudo apt-get update
$ sudo apt-get dist-upgrade
$ sudo apt — purge autoremove
$ sudo reboot
$ sudo apt install raspberrypi-kernel-headers
$ ls /lib/modules/$(uname -r)
$ sudo apt-get install build-essential bc git dkms airmon-ng -y
$ git clone https://github.com/aircrack-ng/rtl8812au/ — branch v5.1.5
$ cd rtl88*
$ sed -i -e ‘s/CONFIG_PLATFORM_I386_PC = y/CONFIG_PLATFORM_I386_PC = n/g’ Makefile
$ sed -i -e ‘s/CONFIG_PLATFORM_ARM_RPI = n/CONFIG_PLATFORM_ARM_RPI = y/g’ Makefile
$ sudo ./dkms-install.sh
$ sudo reboot

i wrote a blog post on this but its in italian if you want you can check it out @MrDrache333 here