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VLANs on /16 networks


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I'm using a Domotz Box connected to a network which is VLAN 1.  I'm trying to add VLAN 2 which is  The configuration page only accepts subnet masks in the range /22-/32.  Any logical reason for this?

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Hi @mark65,


There is indeed a limitation on the size of the main/default network interface and VLANs to be maximum a /22 network mask ( The Domotz Agent if connected to a bigger network only scans the netmask /22 around its IP address. This limit is applied to make it possible to monitor every 30 seconds every address/device on each VLAN, scanning a /16 VLAN (˜65534 addresses) would take much more time than 30 seconds.


However there are some workarounds to monitor the most part of the network without major changes:

a) Configuring the agent main network interface with an IP address between near the gateway, for example, and - near the gateway (the first /22 block would be monitored - from to

Then using the Domotz App or WebApp, you may add 8 additional /24 subnets. e.g. using the Private Subnet Scan.

  1. -
  2. -
  3. -
  4. -
  5. -
  6. -
  7. -
  8. -

*You can customize that accordingly with the blocks you have the most interest in.

So the maximum network covered as it is would be from to (up to 3048 devices). Keeping in mind that the Private Subnet Scan doesn't monitor the MAC Address of the devices, so the monitoring will be based on its IP Addresses, static IP Address is recommended at least for the most important devices. Features like the Topology Map are not supported for devices discovered this way.

b) I really suggest you resize the network/subnets and segregate them using VLANs (up to a /22 subnet) this way with one agent you would be able to cover the entire site, for example:

Place the agent main network interface with an IP address between and (the first /22 block would be monitored - from 10.0.1 to and add the additional VLANs to the agent:

  1. VLAN 2 -
  2. VLAN 3 -
  3. VLAN 4 -
  4. VLAN 5 -
  5. VLAN 6 -
  6. VLAN 7 -
  7. VLAN 8 -
  8. VLAN 9 -

*You can customize that accordingly with the blocks you have the most interest in.

Our recommendation is to configure up to 10 VLANS /22 per agent that would give you the monitoring of 10160 possible devices.


Keep in mind, that if you want to cover the entire network, you can always plan to configure more than one Agent on that network instead of these workarounds. If you want to use a single Domotz Agent without these workarounds,  it may be possible to provide a "Custom" configuration which allows you to configure more than the default 8 subnets. This need to be discussed with our Sales team (sales@domotz.com).


Let me know if you need any further clarification.


Henrique Salvador

Domotz Support



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