troubleshooting DHCPv6 and/or IPv6 routing

shpokas

Hi,
please help to troubleshoot DHCPv6 and/or routing issue.
We had multi-WAN setup for quite a while, but recently had to relocate and one ISP was dropped.
So now we have a single WAN connection and Tunnebroker tunner on top of it.
Two entries in System/Routing/Gateways , one for IPv4 and one for IPv6, nothing else.

Setup
pfSense with Tunnelbroker IPv6 tunnel.
Single WAN connection.
Issue:
DHCPv6 doesn't work. RADVD also doesn't work.
Troubleshooting:
pfSense is picking up DHCP requests, but DHCP addreses don't make back to the client.
dhcpd.log looks like:

Jun  2 17:06:40 gw dhcpd: Solicit message from fe80::20c:29ff:fe5d:2360 port 546, transaction ID 0x1D9D600
Jun  2 17:06:40 gw dhcpd: Picking pool address 2001:470:xxxx:0::848d
Jun  2 17:06:40 gw dhcpd: Advertise NA: address 2001:470:xxxx:0::848d to client with duid 00:01:00:01:26:65:1f:c6:00:0c:29:5d:23:60 iaid = 693969760 valid for 86400 seconds
Jun  2 17:06:40 gw dhcpd: Sending Advertise to fe80::20c:29ff:fe5d:2360 port 546
Jun  2 17:06:40 gw dhcpd: send_packet6: No route to host
Jun  2 17:06:40 gw dhcpd: dhcpv6: send_packet6() sent -1 of 120 bytes

If I re-save interfaces or gateways then system.log has these entries:

Jun  2 17:05:53 gw php-fpm: /system_gateways.php: The command '/sbin/route delete -host ' returned exit code '64', the output was 'route: destination parameter required route: usage: route [-46dnqtv] command [[modifiers] args]' 
Jun  2 17:05:53 gw php-fpm: /system_gateways.php: The command '/sbin/route delete -host ' returned exit code '64', the output was 'route: destination parameter required route: usage: route [-46dnqtv] command [[modifiers] args]'

I suspect that there is some configuration issue that is preventing proper routing setup for LAN IPv6.
But I don't understand how to fix it.
I tried to backup and restore configuration, but that didn't help.
I would appreciate any hints to how fix this.
Thanks,
shpokas

shpokas

@shpokas
I found my old post and the fix was to find and remove "ghost" DNS servers in configuration export then reimport exported configuration.
https://redmine.pfsense.org/issues/8390