I don't see what I'm refrencing, or perhaps I dont understand your dump.
I usually see it a DNS (not RDNS) in the router SLAAC traffic running tcpdump
.
I dont see anything wrong in the config tho - this is what I have:
config dhcp 'lan'
option interface 'lan'
option start '100'
option limit '150'
option leasetime '12h'
option ra 'server'
That sets up IPv6 addresses whether I choose/setup prefixes from a 6in4 tunnel, link-local, ULA, wan6 or any combination.
Lease time config of "1" some one else posted...I'm almost certain thay means 1 second...that's seems odd.