WAN broken after new IP from provider's DHCP

Hi all,

I'm new to this community Image may be NSFW.
Clik here to view. I'm running an ERL at my home for more than a year. I'm very happy with it.

Last wednesday, my fiber provider renewed IP's for many subscribers. After the IP changed, my WAN connection was broken (Network is unreachable), while the webinterface was displaying the new IP on the interface. Disabling -> Enabling the WAN interface (VLAN 34) repaired the connection.

The messages log is showing:

Nov  9 14:29:10 ubnt ipsec-dhclient-hook: DHCP address updated to from XXX.XXX.XXX.old: Updating ipsec configuration.
Nov  9 14:29:11 ubnt xl2tpd[3047]: death_handler: Fatal signal 15 received
Nov  9 14:29:11 ubnt xl2tpd[6957]: parse_config: line 3: set_ip: host '' not found
Nov  9 14:29:11 ubnt xl2tpd[6957]: init: Unable to load config file
Nov  9 14:29:19 ubnt ipsec-dhclient-hook: DHCP address updated to XXX.XXX.XXX.new from XXX.XXX.XXX.old: Updating ipsec configuration.
Nov  9 14:29:20 ubnt xl2tpd[7062]: setsockopt recvref[30]: Protocol not available
Nov  9 14:29:20 ubnt dhclient: send_packet: Network is unreachable
Nov  9 14:29:20 ubnt dhclient: send_packet: please consult README file regarding broadcast address.
Nov  9 14:29:20 ubnt dhclient: dhclient.c:2164: Failed to send 300 byte long packet over fallback interface.
Nov  9 14:29:29 ubnt dhclient: send_packet: Network is unreachable
Nov  9 14:29:29 ubnt dhclient: send_packet: please consult README file regarding broadcast address.
Nov  9 14:29:29 ubnt dhclient: dhclient.c:2164: Failed to send 300 byte long packet over fallback interface.
Nov  9 14:29:40 ubnt dhclient: send_packet: Network is unreachable
Nov  9 14:29:40 ubnt dhclient: send_packet: please consult README file regarding broadcast address.
Nov  9 14:29:40 ubnt dhclient: dhclient.c:2164: Failed to send 300 byte long packet over fallback interface.
Nov  9 14:29:53 ubnt dhclient: send_packet: Network is unreachable
Nov  9 14:29:53 ubnt dhclient: send_packet: please consult README file regarding broadcast address.
Nov  9 14:29:53 ubnt dhclient: dhclient.c:2164: Failed to send 300 byte long packet over fallback interface.
Nov  9 14:30:00 ubnt dhclient: send_packet: Network is unreachable
Nov  9 14:30:00 ubnt dhclient: send_packet: please consult README file regarding broadcast address.
Nov  9 14:30:00 ubnt dhclient: dhclient.c:2164: Failed to send 300 byte long packet over fallback interface.
Nov  9 14:32:14 ubnt dhclient: send_packet: Network is unreachable
Nov  9 14:32:14 ubnt dhclient: send_packet: please consult README file regarding broadcast address.
Nov  9 14:32:14 ubnt dhclient: dhclient.c:2164: Failed to send 300 byte long packet over fallback interface.
Nov  9 14:32:20 ubnt dhclient: send_packet: Network is unreachable

I'm running firmware 1.8.5 and have configured a VPN. I was unable to find possible fixed in the 1.9.0 changelog.

interfaces {
    ethernet eth0 {
        address 192.168.1.1/24
        description LAN
        duplex auto
        firewall {
            in {
            }
            local {
            }
            out {
            }
        }
        speed auto
        vif 2 {
            address 192.168.2.1/24
            description LAN-IPTV
            firewall {
                in {
                    name LAN-IPTV_IN
                }
                local {
                    name LAN-IPTV_LOCAL
                }
                out {
                }
            }
        }
    }
    ethernet eth1 {
        description WAN
        duplex auto
        firewall {
            in {
            }
            local {
            }
        }
        speed auto
        vif 4 {
            address dhcp
            description WAN-IPTV
            firewall {
                in {
                    name WAN-IPTV_IN
                }
                local {
                    name WAN-IPTV-LOCAL
                }
            }
            mac XX
        }
        vif 34 {
            address dhcp
            description WAN-INTERNET
            firewall {
                in {
                    name WAN-INTERNET_IN
                }
                local {
                    name WAN-INTERNET-LOCAL
                }
            }
            mac XX
        }
    }
    ethernet eth2 {
        disable
        duplex auto
        firewall {
            in {
            }
            local {
            }
            out {
            }
        }
        speed auto
    }
    loopback lo {
    }
}

vpn {
    ipsec {
        auto-firewall-nat-exclude disable
        ipsec-interfaces {
            interface eth1.34
        }
        nat-networks {
            allowed-network 192.168.0.0/16 {
            }
        }
        nat-traversal enable
    }
    l2tp {
        remote-access {
            authentication {
                local-users {
                    username XX {
                        password XX
                    }
                }
                mode local
            }
            client-ip-pool {
                start 192.168.1.60
                stop 192.168.1.69
            }
            dhcp-interface eth1.34
            dns-servers {
                server-1 8.8.8.8
                server-2 8.8.4.4
            }
            ipsec-settings {
                authentication {
                    mode pre-shared-secret
                    pre-shared-secret XX
                }
                ike-lifetime 3600
            }
            mtu 1492
        }
    }
}

Thanks for your feedback!

Nick