SNMP Issue

Hello All,

we use extensively Mikrotik Routers and Cacti - therefore we also use extensively the great Mikrotik Plugin from the Cacti Group:
https://github.com/Cacti/plugin_mikrotik

Everything worked fine till we upgraded one of our main PPPoE Concentrators (a CCR1036-12G-4S) from v6.34 to v6.37.1.
Since then, the Cacti Grpahs are distorted, showing bad/wrong values.

See a example here:
https://www.dropbox.com/s/innz6hgnmt11gig/issue.png?dl=0

We upgraded the Ros the 25 - you see that everything before that date shows nicely the Quota usage per session for that User.
After the 25th, the graphs shows flat line with varying - and wrong - data.

Any Idea?
Heiko