I updated the kernel from 3.10.0-514.16.1.el7.x86_64 to 3.10.0-693.2.2.el7.x86_64 . While I was following these steps https://wiki.centos.org/HowTos/Laptops/Wireless/Broadcom
The instructions at https://elrepo.org/tiki/wl-kmod always worked for me (BCM4312, if I remember correctly).