The server running that system needs cooling, yes. You can't just shove it in a closet with zero thought and expect it to not overheat/shut down/catch fire, unless you live in the Arctic.

I have a little fanless mini PC that runs various stuff around my house, including homeassistant. The case is basically a big heat sink.

It started crashing during backups.

The solution was to stick a fan on it. :( This is literally a box _designed to not need a fan_. And yet. It now has a fan and has been stable for months. And it's not even in a closet - it's wall-mounted with lots of available air around it.

You must be young. We used to have handhelds and computers with no cooling at all.

You're saying that as if we never had Z80-based microcontrollers doing all this without problems. Complete with centralized control and all.

There are card access systems that don’t require a computer, just a microcontroller. Perhaps if you need to integrate with multiple sites or a backend system for access control rules you can add computers, but card access systems are dead ass simple for a reason; they need to be reliable. The good systems that have computers still allow access in the event of a network failure.

Any access control system that fails in the event that it loses internet connectivity is poorly designed.