Comment by bigfatkitten
6 days ago
> You should be using dynamic DNS
That doesn't solve the problem. DNS remains broken until each and every device, assuming VERY generously that it is capable of dynamic DNS at all, realises that one of its prefixes has disappeared and it updates its DNS records. With DNS TTL and common default timeouts for prefix lifetime and router lifetime, that can take anywhere from 30 minutes to 30 days.
> and firewall rules should be on the subnet boundary in this scenario, any decent firewall (including referee PFsense/OpnSense) support ACLs that follow IPv6 address changes.
This requires you to assign one VLAN per device, unless perhaps you've got lots of money, space, and power to buy high end switches that can do EVPN-VXLAN so that you can map MAC addresses to SGTs and filter on those instead.
> each and every device ... updates its DNS records.
What device on your office LAN should maintain its own DNS records? Advertise your own caching DNS server over DHCP(6), give its responses a short TTL (10 sec), make it expire the relevant entries, or the whole cache, when one of your links goes down. I suppose dnsmasq should handle this easily.
It seems that the discussion turned away from a multi-homed setup (pooling the bandwidths of two normally reliable links) to an HA/failover setup (with two unreliable links, each regularly down).
Every device.
It either needs to be able to update DNS by itself (a la Active Directory), or it needs to be able to give the DHCP server a sensible hostname in order for DHCP to make this update on its behalf, which most IoT devices cannot.