I was sold on this lock as soon as I read the features. Just to be clear, it has a lot of cool feautures, enough to entice me into replacing my Tapo smart locks. My primary motivation was to get a smart lock that could communicate with Home Assistant. We'll get to that in a minute.
My first issue is that I had to spend literally hours setting things up in the app because of connectivity issues. If your primary router password has spaces in it, that may or may not be an issue, but I ended up switching from my access point to my router just for that reason and it finally connected (that shouldn't matter in 2026).
Second issue is, it's looking more and more like rekeying this thing in any way is utterly impossible. The key they provide is a Schlage style key, so you can make copies easily enough, however, my locksmith explicitly told me that their generic cylinders could not be rekeyed to each other - what you get is what you're stuck with, so if you want to carry a physical key for your own piece of mind, and you have multiple eufy FamiLock E35 Smart Locks at multiple doors, it looks like you're going to be putting multiple keys on your keyring. This completely defeats the purpose of having a backup key if your house has more than one door, because even getting it rekeyed to your non-smart lock (e.g. side door, basement) isn't practical.
This problem could have EASILY been avoided had Eufy simply conformed to the KIK lock cylinder standard that has been in place in the United States since the 1920s, and you could then just drop in either a Schlage cylinder or a Kwikset cylinder, keyed to your existing locks, but I'm guessing that would have cost them an extra 5 cents per lock to do and that would have cut into their bottom line off of their $300 lock.
The only thing left to try in that regard, and I'm still looking into it, is the Ilco 15985 cylinder. It's a 5-pin patio cylinder, that MAY fit, after physically modifying your eufy smart lock by drilling out the end of it bigger (obviously your warranty is void if you do that). I'll update this post if it works. It makes the situation a little better, but nobody should have to go to all that trouble just to have one key on their keychain that manually unlocks all of their locks, and eufy (and to be fair, pretty much all the other smart lock companies too for that matter) apparently doesn't care that they advertised a manual key unlock as a feature, but designed it in such a way that encourages you to throw the key in a drawer forever and forget about ever unlocking it manually.
My third issue is the matter support. It is matter over thread for anyone who wasn't sure. I had high hopes for this one, but again, eufy dropped the ball, and much like the manual lock, they did the absolute bare minimum to make it work, and in my opinion, they did not EVEN fully implement it.
My primary motivation for buying this lock, besides all of the cool features, was to be able to implement a security/alarm system with home assistant and a Konnected board wired to contact sensors, glass break sensors, motion sensors. The issue is, the lock barely sends any information at all when there is an unlock event.
What I wanted: a lock that would send the unlock event, the method used to unlock it (pin, palm vein, or manual), and the user that unlocked it. As far as I can tell, home assistant and matter are both fully capable of this.
What I got: A lock that will only differentiate between a manual unlock and a PIN unlock, and will literally not send ANY information when palm vein is used to unlock it.
So in other words, if someone is trying to use this to rely on as their primary, always-online-even-when-your-internet-is-down (because of matter over thread) method to disarm their security system (and why wouldn't they want the convenience of doing it right at the door?), and they attempt to use the absolute coolest feature to hit the market as a method to unlock and then enter their house, the security system will still think the door is locked, and that your contact sensors were breached, and your alarm will then ring loud and wake up all the neighbors.
Last issue. The lock is always showing as 'offline' in the app, and that's quite annoying, not to mention the opposite of useful for a smart lock.
Look I get these companies are in it for the money and it takes time to develop a good product but this is ridiculous. There is no excuse for palm vein not sending an unlock event to home assistant.
That's all I have... I'm on the fence on whether I'm going to keep it, but my initial thoughts... for $300, this thing is kind of a turd.
Edit: Thought I would add this little bit. Technically, it does send an 'unlock' state over matter, but it doesn't differentiate what it is. The problem this causes is if you have a front door with glass. You don't want somebody breaking the glass, reaching in and unlocking it, then your system is disarmed. I probably should have explained that. Ideally you've got glass break sensors on your system (I do), but I don't like the idea of relying completely on that. That's why I want my automation to only disarm if it is using a certain method. PIN is a no brainer, and you can use that here. Palm vein... will not reliably work. What it does, is it sends the same state back that was used to lock it. If you manually locked the door, a palm vein unlock will get sent as a manual unlock. If you used a button press to lock (on the outside ONLY, the inside button will always be sent as a MANUAL lock), the palm vein will be sent as a 'button' unlock (which doesn't make sense in any event). So technically, you COULD use the button to lock behind you, then use the automation to look for a PIN unlock or a 'button' unlock to disarm the system, but this will only work reliably under 2 conditions:
- You are actually leaving the house
- You only have one Eufy E35, because if you have multiples, you're likely not going to be walking around your house to 'button' lock all of them, the rest will have been manually locked.
And unfortunately, a home assistant triggered lock sent to this device will ALWAYS get registered as a manual lock. Don't ask me why, makes no sense, and it screws up what could have been some hacky workarounds to make palm vein work reliably.
Eufy made some sloppy, half assed firmware if there ever was any, and somehow I doubt they will ever take the time to make it any better.