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real 280m38.752s
user 17m9.765s
sys 3m36.062s
Ah, I spoke too soon, and have been debugging this for a while. I found bunches of posts, but should have started at Common F30 bugs - Fedora Project Wiki.
Broadcom wireless adapters using proprietary broadcom-wl driver do not work reliably
Multiple users of wireless network adapters supported by the proprietary broadcom-wl driver have reported that it does not work reliably in Fedora 30. PLEASE NOTE that Fedora does not provide or support this proprietary driver; we are providing this note only as a courtesy as we are aware that many people acquire the driver from a third party and use it on Fedora.
The problem seems to be that a new feature in wpa_supplicant that was enabled in Fedora 30 confuses the broadcom-wl driver. As the driver is not open source we cannot provide a fixed version of it, and we will not disable a useful wpa-supplicant feature just to make a proprietary driver work correctly.
To help out folks with affected devices, Davide Caratti is providing unofficial rebuilds of wpa_supplicant with the feature in question disabled. You can enable his COPR repository by running sudo dnf copr enable dcaratti/wpa_supplicant , and then updating your system should install his rebuild, if it is currently up-to-date compared to the version in the official repositories. With this rebuild installed, the wireless adapter should work reliably.