I have a network with a router and a switch. At first my ISP's optical fiber is connected with media converter input port. Than Ethernet cable (output port of Media converter) is connected with the switch. Then an output Ethernet cable is connected with our inner Microtik router. Then this router is connected with another LAN switch. From this switch we have got every connection other switch. It is our total network structure. Our bandwidth is 2 Mbps. From the 11th of March our MRTG graph shows high all the time even when my all switch is switched off except LAN switch. That's why our line is breaking up (Voice call). How could be it possible? My all PC's bandwidth is limited but when connected PC with media converter directly then the graph shows normal. That's why I can't blame my ISP.