https://stainless.corp.google.com/search?view=matrix&row=model&col=build&first_date=2018-06-16&last_date=2018-07-13&owner=%5Echromeos%5C-test%24&suite=%5Ewifi%5C_matfunc%24&status=GOOD&status=FAIL&status=ERROR&status=ABORT&reason=hostapd+process+terminated&exclude_cts=true&exclude_not_run=false&exclude_non_release=true&exclude_au=true&exclude_acts=true&exclude_retried=true&exclude_non_production=false

The stumpy router is not detecting the other interface. It is showing just one interface.

localhost ~ # iw list | grep phy                                               
Wiphy phy0
		 * set_wiphy_netns

@Anthony: Can you check if the other wifi chip went bad on the router.