

Best thing to do here is buy a Network interface card with 2 ports that support a floating IP address for HA. each interface can plug into a separate lan switch for HA.
Last time I did this, broadcomm was a good choice.
I would not run any core services on WiFi only.
How many users ? How large a network? Could you offload dhcp/DNS to other devices to improve resiliency?

Have you looked at just having a dhcp hot standby.
https://oneuptime.com/blog/post/2026-03-20-set-up-dhcp-failover-high-availability/view
It offers better redundancy than just 1 host. Super easy to setup too.