RT-N66 Merlin reboots when N-18 connected to it reboots

[stylish_me]

Hi guys.
I've got a strange problem with rt-n66 running Merlin.
192.168.1.1 is rt-n66 Merlin.
192.168.1.2 is rt-n18 Asus latest firmware.
192.168.1.3 is rt-n16 Merlin.

n16 and n18 are both connected via wire to n66 and are both working in AP mode.

When i reboot n16 - everything is normal. I mean software reboot (schedule or button in UI).
When i reboot n18 - n66 looses WAN connection.

RT-N66 log:

May 7 12:58:10 WAN(0) Connection: WAN was exceptionally disconnected.
May 7 12:58:10 rc_service: wanduck 4777:notify_rc restart_wan_if 1
May 7 12:58:13 dnsmasq[4780]: read /etc/hosts - 5 addresses
May 7 12:58:13 dnsmasq[4780]: read /etc/hosts.dnsmasq - 2 addresses
May 7 12:58:13 dnsmasq-dhcp[4780]: read /etc/ethers - 5 addresses
May 7 12:58:13 dnsmasq[4780]: using nameserver 213.108.16.3#53
May 7 12:58:13 dnsmasq[4780]: using nameserver 178.215.65.250#53
May 7 12:58:16 custom script: Running /jffs/scripts/wan-start (args: 1)
May 7 12:58:16 rc_service: udhcpc 26995:notify_rc start_firewall
May 7 12:58:16 start_nat_rules: apply the nat_rules(/tmp/nat_rules_eth0_eth0)!
May 7 12:58:16 dnsmasq[4780]: read /etc/hosts - 5 addresses
May 7 12:58:16 dnsmasq[4780]: read /etc/hosts.dnsmasq - 2 addresses
May 7 12:58:16 dnsmasq-dhcp[4780]: read /etc/ethers - 5 addresses
May 7 12:58:16 dnsmasq[4780]: using nameserver 192.168.0.1#53 for domain hi.link
May 7 12:58:16 dnsmasq[4780]: using nameserver 192.168.0.1#53 for domain hi.link
May 7 12:58:16 dnsmasq[4780]: using nameserver 213.108.16.3#53
May 7 12:58:16 dnsmasq[4780]: using nameserver 178.215.65.250#53
May 7 12:58:16 dnsmasq[4780]: using nameserver 192.168.0.1#53
May 7 12:58:16 dnsmasq[4780]: using nameserver 192.168.0.1#53
May 7 12:58:16 wan: finish adding multi routes
May 7 12:58:17 dnsmasq-dhcp[4780]: DHCPDISCOVER(br0) 28:e7:cf:e4:ab:ee
May 7 12:58:17 dnsmasq-dhcp[4780]: DHCPOFFER(br0) 192.168.1.95 28:e7:cf:e4:ab:ee


What can be the problem? N66 has hilink usb modem connected in DUAL WAN mode. But it's not a problem when n16 reboots.

 

[stylish_me]

Any ideas?