The Aqara U400 isn’t special to me because it has a million ways to unlock (it does). It’s special because it’s the first lock I’ve tried that can actually support my preferred method of entry: walking up to the door like I own the place—no tap, no app, no “wait… wait… okay now it unlocked.” This video is less of a lock review and more of a protocol video about what changes when Ultra Wideband (UWB) is the thing doing the “walk up and open” experience people thought Bluetooth was already delivering. I break down the three protocols that matter here: Matter (multi-admin and controller flexibility), UWB (intent + tight radius + fast unlock timing), and Aliro (not usable yet as of mid-January 2026, but worth future-proofing for). I also talk about Thread for reliable connectivity, and how Apple HomeKey Express mode is where the UWB magic lives—plus how approach direction settings can help reduce accidental unlocks. My big takeaway: smart locks are at the end of the “arms race” where the winner is whoever crams the most unlock methods into a black rectangle. I think the next era is fewer methods, better ones—key + biometric + phone (ideally UWB)—so locks can finally start looking good again and basically disappear in daily use.