In LibreNMS, you can hit the “Show RRD Command” to give you the command to manually create a graph.  Copy the command.

In the command below, the path shows the IP address of the device to generate the graph from.  Theoretically you can change that to a different IP to generate graphs from other devices.

SSH into server server and run the command, change /tmp/randomtext to something like /root/mikrotik_092619.png or whatever you want.  You can also adjust the size, color etc of the graph.

 rrdtool graph /tmp/randomtext --alt-y-grid --alt-autoscale-max --rigid -E --start 1515946500 --end 1516551300 --width 1712.7 --height 483 -c BACK#EEEEEE00 -c SHADEA
#EEEEEE00 -c SHADEB#EEEEEE00 -c FONT#000000 -c CANVAS#FFFFFF00 -c GRID#a5a5a5 -c MGRID#FF9999 -c FRAME#5e5e5e -c ARROW#5e5e5e -R normal --font LEGEND:8:DejaVuSansMono --font AXIS:7:DejaVuSansMono -
-font-render-mode normal COMMENT:'Volts Cur Min Max\n' DEF:sensor495=/opt/librenms/rrd/192.168.88.1/sensor-voltage-routeros-0.rrd:sensor:AVERAGE LINE1:sensor495#CC0000:'Voltage 0
 ' GPRINT:sensor495:LAST:%5.1lfV GPRINT:sensor495:MIN:%5.1lfV GPRINT:sensor495:MAX:%5.1lfV\l