What is this firewall? The one in the router or something else? Since when did a (software/firmware) firewall have its own IP address?
If Daisy have only routed the 2300 (/64) in the /56, then pings to LAN 2301 will not get go anywhere.
Most here seem to me to be grossly over-complicating this. The OP is not setting up his LAN as specified by Daisy. Before trying the strange 2301, for heavens sake can't we get the Daisy-specified setup tried?
The firewall is built in the UDM Pro, I haven't added any rules for IPv6 yet.
What should I use for the LAN?
Here's how Ubiquiti say it should be setup:
WAN
IPv6 Connection Type: Static IP
IPv6 Address: 2001:db8::1
Prefix Length: 64
Router: 2001:db8::2
LAN
IPv6 Interface Type: Static
IPv6 Gateway Subnet: 2001:db8:1::1/64
IPv6 RA: Checked
IPv6 RA Priority: High
DHCPv6: Checked
DHCPv6 Range > Start: 2001:db8:1::2
DHCPv6 Range > Stop: 2001:db8:1::7d1
DHCPv6 Lease Time: 86400
DHCPv6/RDNSS DNS Control: Auto
DHCPv6/RDNSS Name Server > DNS Server 1: <customizable>
DHCPv6/RDNSS Name Server > DNS Server 2: <customizable>
DHCPv6/RDNSS Name Server > DNS Server 3: <customizable>
DHCPv6/RDNSS Name Server > DNS Server 4: <customizable>
https://help.ui.com/hc/en-us/articles/115005868927-U...