I have been trying for some days now to get an Alfa AWUS036ACS USB adapter installed on an RPI running Buster. This adapter uses the RTL8811au chipset but everyone seems to use the rtl8812au drivers.
The problem I seem to be having is monitor mode doesn't work with the standard drivers so a specific set of drivers needs to be used.
I have followed lots of instructions but this one seems to get the closest - Install drivers for RTL8812au for raspibian kernel 4.14.79-v7+ or 18.104.22.168-v7+?
However when I follow the instructions for the edited comment by Jake specific to Buster using dkms I get the following error when running command
sed -i 's/^dkms build/ARCH=arm dkms build/' dkms-install.sh
The error being
sed: can't read dkms-install.sh: No such file or directory
Not sure what to try. The install is going onto a fresh build of Buster with the only other addition of
sudo apt update being run.
I presume it has something to do with the RPI4 being a 64bit platform?