I am a noob at this and struggle to get the correct answer for this "bug".
I finally got the WiFi to work!
What I did:
- connect Raspberry Pi 3 via LAN (with internet connection)
- copied 3 files (brcmfmac43455-sdio.bin, brcmfmac43455-sdio.clm_blob and brcmfmac43455-sdio.txt) to the path /lib/firmware/brcm/* from this link https://github.com/armbian/firmware/tree/master/brcm
(I read on other posts that this would fix it, but it didn't!)
- run the following command to copy a txt file need:
[root@rpi3 ~]# curl https://fedora.roving-it.com/brcmfmac43430-sdio.txt
(without it wlan0 would not appear in devices)
- you also need to update NetworkManager, if not the wlan will appear with a "missing plugin" error and won't work:
[root@rpi3 ~]# yum install NetworkManager-wifi
-finaly reboot your raspberry pi with the "reboot" command, now you should have wlan0 up and running, all you need to do is run the command to connect to wifi and you are all set.
(I don't know if this information is in the right place, but when I searched for the rpi3 ol7 wifi problem this is one of the first pages that had resulted. so in hopping that it will help others I wrote the reply here)
Hope it helps!