After upgrading to macOS 14 I had a weird networking problem — nothing in, nothing out. The interface config looked fine, so DHCP had worked. Same on Wi-Fi and Ethernet, with and without firewall switched on.

But below the firewall button, under Filters, there was Little Snitch! Switched it off and lo, it worked.

Paging nostr:npub1psdfxfpxz2cwmmnsk60y3nqpn2tqh9n24h4hstvfkwvr6eaek9js499sr7 as he intended to upgrade, too.