4G Router link is flapping

Question

Hello, 
 
 We ditch out our ADSL lines for cost cutting reason, we acquire a bunch of 4G routers, and we have this strange issues of links are coming up and down from the email notifications, automatic uplink monitoring is turned off and we point the monitoring host to 8.8.4.4 google dns server, i check the service monitors and im always seeing this logs, kindly explain please what is the meaning of this;

2018:02:19-08:08:43 astaro service_monitor[22749]: id="4002" severity="info" sys="System" sub="loadbalancing" name="ICMPv4 out of sequence!" 
 2018:02:19-08:08:42 astaro service_monitor[22749]: id="4002" severity="info" sys="System" sub="loadbalancing" name="ICMPv4 out of sequence!" 
 2018:02:19-08:08:42 astaro service_monitor[22749]: id="4002" severity="info" sys="System" sub="loadbalancing" name="ICMPv4 out of sequence!" 
 2018:02:19-08:08:42 astaro service_monitor[22749]: id="4002" severity="info" sys="System" sub="loadbalancing" name="ICMPv4 out of sequence!" 
 2018:02:19-08:08:43 astaro service_monitor[22749]: id="4002" severity="info" sys="System" sub="loadbalancing" name="ICMPv4 out of sequence!" 
 2018:02:19-08:08:43 astaro service_monitor[22749]: id="4002" severity="info" sys="System" sub="loadbalancing" name="ICMPv4 out of sequence!" 
 2018:02:19-08:08:43 astaro service_monitor[22749]: id="4002" severity="info" sys="System" sub="loadbalancing" name="ICMPv4 out of sequence!" 
 2018:02:19-08:08:43 astaro service_monitor[22749]: id="4002" severity="info" sys="System" sub="loadbalancing" name="ICMPv4 out of sequence!"

Arvin Carlos · Accepted Answer

Hello, 
 
 The four 4G routers we acquire is using CGNAT from the ISP, maybe the NAT is overwhelmed or max multiplexed from the ISP side, and we cannot find a good host outside for the link monitoring, even making it to point to google dns servers and using UDP 53, also checking the automatic monitoring will make it worst since Sophos is using root DNS servers which the routers sometimes cannot contact, a solution we made, since the three WAN links are DHCP's, we point the host monitoring to its local gateway (private IP's)..is this a good practice? but this is only the stable solution for now that is working. 
 
 2018:02:22-12:02:37 astaro service_monitor[26623]: id="4000" severity="info" sys="System" sub="loadbalancing" name="multipath 3 ICMP 192.168.79.1 changed state to ONLINE" 
 2018:02:22-12:02:37 astaro service_monitor[26623]: id="4000" severity="info" sys="System" sub="loadbalancing" name="multipath 1 ICMP 192.168.77.1 changed state to ONLINE" 
 2018:02:22-12:02:37 astaro service_monitor[26623]: id="4000" severity="info" sys="System" sub="loadbalancing" name="multipath 4 ICMP 192.168.80.1 changed state to ONLINE" 
 2018:02:22-12:02:37 astaro service_monitor[26623]: id="4000" severity="info" sys="System" sub="loadbalancing" name="multipath 2 ICMP 192.168.78.1 changed state to ONLINE"