Usually missing wifi firmware can be solved without internet this way: - look into dmesg. It will tell you which firmware file is missing. - go (on another ma

Usually missing wifi firmware can be solved without internet this way: - look into dmesg. It will tell you which firmware file is missing. - go (on another machine) to packages.debian.org, enter the filename into "Search the contents of packages" form - download the package and transfer it to the target machine (usb stick, smoke signals, whatever) - either install it as is (dpkg -i) or extract it (dtrx package.deb, then dtrx data.tar.gz), pick that one file and place it to /lib/firmware