router problems

We have a network of six intel switches connected to central intel switch router, we divided the network with vlan configurations, with all in one subnet. We have about 150 computers in our network.
The problem is that sometimes the router stops and we have to reset it to resolve the problem, we are not knowing from where the problem originates, there is a switch that we can’t communicate with sometime and gives a red light in the intel device view program as if it is still functioning and theclients connected to this switch can communicate with the network but we can’t update the vlan configuration.