I do have a RUT240 router and seems to have an issue after the reboot. DDNS is not working, this because DNS is not working at all. I configured the DNS server of google at the WAN side but even than it failed.
I logged into the RUT240 via SSH and executed the following command:
echo nameserver 188.8.131.52 > /etc/resolv.conf
After executing that command, DDNS start working and also able to ping a domain name with success.
How do I make this a permit solution? There is no /etc/network/interfaces file on the router.
Waiting at your suggestions.