For computers from the early to mid 2010s in particular, the wifi card might be reported as not fitted or working. try these steps.
Reset the SMC Reset the PRAM Remove the file: /etc/sysctl.conf The problem might be wifi/Bluetooth cable, it runs over the disc drive and is prone to failure.
My latest blog post: Ask Doctor Google: Do I not trust doctors? Well, to some extent I do, but I would prefer an AI any day! (posted 2026-05-06).