After upgrade from 24 to 25 local IPv6 addresses no longer resolving

Installing and Using OpenWrt
1

I’ve recently upgraded via attended upgrade from 24.10 to 25.12 on an x86 device, and it is no longer resolving IPv6 DNS queries for devices on my LAN. I have some devices on the network that are IPv6 only so they no longer resolve at all - but even those with IPv4 addresses won’t resolve if I force a v6 query.

  • The devices are getting allocated IPv6 addresses
  • When I switch on DNS logging I see NODATA-IPv6 in response to the ping -6 queries
  • In /tmp/hosts/odhcp I can see the entries are there (with a # at the start of the line - not sure if that’s normal)

Looking at the list of addresses in Luci it does look like the IPv4 addresses and the IPv6 addresses are not being associated with each other - they don’t have the .lan in brackets like they do for the IPv4 addresses. In the odhcp file the names are there but with a capital at the start and no .lan suffix. Again, not sure if that’s normal.

I’ve tried diagnostics with both ChatGPT and Claude but not had much luck…

Any suggestions would be appreciated :slight_smile:

2

This fixed it:

uci set dhcp.odhcpd.hostsdir='/tmp/hosts'
uci set dhcp.odhcpd.leasefile='/tmp/odhcpd.leases'
uci commit dhcp
/etc/init.d/odhcpd restart

This moved the leasfile out of /tmp/hosts, but created a bunch of vlan-specific files that contained the entries for dns resolution. Previously there wasn’t an entry for dhcp.ohcpd.hostdir in the config. Clearly something must have tightened up in OHCPD between the version used in 24.10 and 25.12.

Don’t know if there are unintended consequences…but for now at least it’s working!

3

I also had to include this line - for some reason it wasn’t there on one of my vlans:

dhcp.[interface name].ra_flags='managed-config' 'other-config'