no wireless with Debian, Fedora, or TrueOS but ok with old Knoppix or Porteus OSes
Wi-Fi is nonexistent when TrueOS or Fedora 25 Linux are installed or Fedora 20 or 25 is live or Debian 8.8.0 is installed but works fine when old Knoppix 7.2 is either installed or run live or with Porteus 1.1 64-bit running live on the same laptop. These are all Linux except that TrueOS is FreeBSD. In nonroot TrueOS (version of 2017-04-21), I tried treating my usual home network as hidden but that only got me a profile, not a connection, although the icon is on the Lumina desktop. TrueOS > SysAdmin: Update Manager (127.0.0.1) window > Updates tab > Latest Check > "System is up to date!!" implies Internet access works but I think that message is probably an error, especially since the title bar shows a loopback address. In Fedora, the wireless icon is missing from the desktop panel, wireless is not in the network app, and it doesn't work. Debian with the Xfce desktop in nonroot (root was unreachable) didn't see any wireless. (I didn't test TrueOS root since I had to replace it with Debian but would like to reinstall TrueOS.) All this is on a refurbished Dell Latitude E4300 laptop, recently bought, all single-boot. I never tried Windows, which I erased. I'd rather do my own repairs. What should I fix in the laptop or is it entirely an OS or app issue?
RE: no wireless with Debian, Fedora, or TrueOS but ok with old Knoppix or Porteus OSes
Tentatively solved (I'm the original poster): I got a USB Wi-Fi NIC meant for Linux without having to compile or install any software (it's from ThinkPenguin) and it's working. Regarding my other attempts, I think a driver may have been taken out of the Linux kernel, which would be why old OSes worked but newer ones did not.