Can't join world via LAN

My brother has a world that he plays Survival on. He has played it fine on a cracked account until the 24th. The world is hosted on my computer. He got a premium account on the 25th (his bday). When I hit Open to LAN, it "works", but he doesn't see the world in the list. I am certain that we are on the same WiFi network. I've tried many things, such as hitting Refresh, turning off WiFi on his end for at least 10 secs, etc.