upload traffic does not add up

Hi

Have any of you ever had a situation where the upload traffic doesn't go down as it should during the night ?

usually the upload traffic at night goes down near zero

We have upload traffic during the night and if we do an addition of each individual modem the total traffic doesn't fit with the reported traffic we see on the monitoring

So it's like "ghost" traffic, it is not sent by the modems but it appears in the cmts interface.

If we reset the modem then the traffic will go down to zero of course but after a couple of days it comes back slowly, each day a little more "ghost" traffic appears

on the graphs the timeline is toward the left