Mac connects to iPhone hotspot but no internet

I'm trying to set up a hotspot, sharing the connection from an iPhone X running iOS 12.1 with a MacBook Pro running macOS Mojave. The hotspot is working fine and other devices can connect to it and use the internet, but although the MacBook connects to the hotspot OK, browsers don't work. The MacBook can ping the DNS server set by the phone's DHCP, and other servers, but lookup fails (dig, nslookup or the network utility tool), and all browsers report that there is no internet connection. I've tried going through the answers to this question but nothing seems to have made any difference. Both devices have been restarted multiple times, and I've reset the phone's network settings.