Link Down "Packet Loss" but RRD=~10% but high mark is 35% in Routing !?

[Nachtfalke]

Hi,

I have some problems with packet Loss on my WAN1 interface. This is because in front of this line there is very old equipent and so there is often some traffic loss.
To avoid, that my WAN1 does a failover many times a day because of this behaviour, I highered the Packet Threshold from 25% - 35%.

I checked the RRD graph in the past to find the highest limit but now I am not sure if the RRD is really exact or if there is another problem with my WAN connection.

I attached you some screenshots.
The link went down on 11:57 and came up again on 11:58
The RRD graph say maximum loss is less then 10% !?

How could I find out how high the packetloss was really ?