Network configuration can be complex, and the failure modes of a network can be difficult to predict. This article outlines some issues that are generic to IP/Ethernet based local networks.


If you cannot communicate from nControl (CompactControl) to nBox/CompactUtm/Megawall, there are a few things you can check.


Windows Firewall

The windows firewall must be configured to allow nControl (CompactControl) to communicate on the network. Since windows differentiates between "Work", "Home", and "Public" network, make sure that nControl is allowed to communicate on all network types.


Network address and mask

Ensure that the network address of the nControl (CompactControl) computer is set to be part of the same subnet as the nBox/CompactUtm/Megawall. Also check that the subnet mask is the same on all devices on the network.


Routers and bridges

nControl (CompactControl) uses UDP broadcast to establish initial communication with devices on the network. This means that broadcast must be allowed by any routers or bridges between nControl and nBox/CompactUtm/Megawall. If there is a router or bridge between the devices (not recommended) this router/bridge should be configured to pass through broadcast, and if it has a firewall function, this must be disabled.


IP address issues / conflicts

When an IP address of a device in the system is changed, it may take some time for other devices to pick up this change and update their routing tables. If an IP address conflict is suspected, the safest solution is to power down all devices (including computers, printers, routers, network disks, switches, bridges, and routers) on the subnet, and then power them back up. This ensures "clean" routing tables in all devices.


IP address conflicts may occur in a number of situations:

  • When changing the IP address of a device to one that is already in use
  • When changing the IP address of a device to an address that was recently in use
  • When setting the IP address of two devices to the same
  • When using combinations of DHCP (automatic) addresses and manual addresses
  • Other changes to network structure
  • Cable issues 

In some rare cases, a cable or switch fault has led to a situation where traffic can be sent one way but not the other. To eliminate this as a potential problem, try different sets of cables, and if possible, different ports on switch/patch panel/router.