There are times when some of the information on the graphs in Zabbix is missing, so to say it is displayed partially and with interruptions.
I will describe possible reasons for interruptions and their solution:
1) There may be a bad connection to the network node, you need to check the ping from the Zabbix server to the network node.
For example, the first PING command with large packages from Windows, and the second from Linux:
ping -t -l 1024 192.168.5.1 ping -i 0.2 -s 1024 192.168.5.1
2) The device is slow to work and stops responding when there are a large number of requests, in order to solve this problem it is necessary to uncheck “Use mass requests” in the settings of the Zabbix network node.
3) 32-bit counters are used to obtain data from the network node, and when loading device interfaces, for example, above 400 megabits, the data on the graph may not be displayed; in order to solve this problem, in the data elements, they must be replaced with 64-bit ones and the node’s network history is cleared in order there were no leaps.
For example, if traffic is received from the first network interface via the ifInOctets.1 MIB (32-bit), then it must be replaced with ifHCInOctets.1 (64-bit).