Hello, first attempt so please kindly let me know if this is not the correct place.
Background
I am running UTM 9.411-3 in a home environment virtualised on Proxmox. My previous setup had multiple virtual network interfaces, one for each VLAN (and subnet) but I currently have two interfaces, one on the VLAN connected (through switches and a trunk) to the VDSL modem and the other connects to a layer 3 switch. Thereafter, the switch handles the inter-VLAN routing and has the UTM set as the default gateway.
First question
My ISP is IPv4 but I have a Hurricane Electric /48 IPv6 connection. If I set the internal interface on the UTM to be dual stacked (with any IPv6 address, but essentially either /64 routed or a /64 subnet from my routed /48 range) then the interface is shown as [down] and DHCP does not run. Occasionally it can be persuaded to be [up] with some rebooting and toggling on and off but it is a nuisance. Either up or down, the IPv6 routing works and all machines on the subnets can connect dual-stacked but without the benefit of IPv6. Is this correct? The workaround appears to be to create two interfaces (one v4 and one v6).
Second question
My other problem is with IPv6 DHCP relay. I would like the UTM to serve addresses for v4 and v6 via DHCP. V4, correctly, requires the range to be within the subnet of the adapter unless the relay option is selected. IPv6 appears to never permit a DHCP range to be set that does not match the adapter interface, irrespective of the relay setting. Is there a workaround for this or am I doing something wrong? I have the switch set to relay on v4 and v6 but my only solution to date has been to set the interface to a /48 subnet (so my DHCP ranges are within the scope of the adapter) and insert routing rules for the individual subnets.
Please accept my apologies if I am being an idiot, I do not work in IT, it is merely a hobby for me.
Many thanks,
Andrew