Daemon.warn odhcpd[858...no public prefix on br-lan

HI, I was checking my system log and the following message is appearing serevela times:

daemon.warn odhcpd[858]: A default route is present but there is no public prefix on br-lan thus we don't announce a default route!
daemon.info odhcpd[858]: Using a RA lifetime of 0 seconds on br-lan

I am using a VPN cliente with open vpn on the router and change my isp DNS.

Can someone help me in order to explain what is happening please. Apparently everyting is working good (internet access no reboot....)
Many thanks

What router?

What firmware and version?

Does it happen without using VPN?

There was an old bug that has since been fixed...

Your router doesn't advertise a default IPv6 route for lan devices since it says there is no public IPv6 address configured on the lan interface.

If you don't expect working IPv6 for lan devices then I guess it can be ignored.

Hi, thank you for thin information.

I am using:
TP-Link Archer C7 v2
LEDE Reboot 17.01.4 r3560-79f57e422d / LuCI lede-17.01 branch (git-17.290.79498-d3f0685)
yes it happen without using vpn. The error happen with and without VPN. This is strange...if it was fixed why it happens?

I found that if I go to Lan interface-DHCP server-IPv6 Settings and enable "Announce as default router even if no public prefix is available." the error does not happen!

Thanks for you help