The relaxed position of mammalian eyelids leaves them open. Muscles must contract for the eyes to be shut. Dead creatures cannot contract their muscles so their eyes remain open after they die.
You cannot shut their eyes for them by closing their eyes with your hand. Morticians place contacts in cadaver's eyes while preparing the body for a wake. Those contacts grip the inside of the eyelids so that they remain closed.
This is why some cultures have funerary traditions in which objects are placed over the eyes.
TL;DR: you and your loved ones won't close their eyes when they die.


I'm a bit late to the party. I was a network admin in another life and believe I can help out. I've skimmed existing conversations but not fully poured over them.
That said: I'd print the routing tables for the switches and firewall and review them. Considering firewall rules is sensible but it seems you've already done quite a bit of investigation there. It sounds like there is some vlan configuration missing. Like one of the switches doesn't have the vlan interface defined or named in its vlan database.
Review the routing tables and confirm who owns each vlan and what those networks are aware of. Also toggle your logging options on so you can review them and test with more info than pass/fail.
It very well may be a OPNsense firewall knowledge thing but I'm not convinced. If you're still working on this tomorrow I'd be happy to help root-cause the problem and fill in the gaps between RTFM and old YouTube videos. :)