Munin on Ubuntu 16.04 - Empty network graphs

i have strange issue munin on ubuntu 16.04. graphs ok network traffic , errors empty.

i see nothing in logs it, , running:

munin-run if_eth0

gives output:

down.value 5382101121 up.value 79038417951

which seems ok me. running if_err_eth0 works too, graphs this:

how can fix strange behaviour?

ok, found problem was. munin unable determine ethernet connection speed, , in details of traffic graph reporting:

maximum speed -1mb/s.

i don't know if issue global ubuntu 16.04, not here on same cloud instance prior versions of os.

to fix it, forced link speed in plugin's configuration (/etc/munin/plugin-conf.d/munin-node):

[if_*] user root env.speed 1000

Primitatvve