@Virgo 

The graphs above show the dynamics of incoming packets on the router port to which the switch port is connected, and outgoing packets on the switch port.

These graphs must match.

In practice, these charts not only don't match, they don't even match trends.

Hence the conclusion - the router in the "standard" OIDs gives garbage.

  @mzd6 Have you had any success with this ? I am receiving the exact same issue on my ER605, namely that standard SNMP monitoring of an interface is not returning figures indicative of the traffic actually passing through that interface.

-Pete

  @Pete_G_67 

unfortunately, no..

  @mzd6 any updates? here i have the same issue.

  @renatolopes 

Nope. Moreover, there were two times that the router stopped sending SNMP data until I rebooted it.

You may be experiencing counter wrapping.  I don't know how Zabbix or LibreNMS handle that.  Debugging a similar situation on my NMS, the following is the raw data polled from SNMP from an OID that is supposed to be HC In Octets:

While the data is coming from the HC OIDs, the actual values are not 64 bit.  They seem to be wrapping on the router itself in a 32 bit data type.

If I'm right about this, the only way this can be fixed is with a firmware update on the router.

  @CheetoBandito 

Also having the same problem trying to monitor this unit.

Is TP-LINK going to chime in on this issue and provide a fix?