This scenario will explain how to managed UniFi Access Points across multiple subnets with only one UniFi Controller

As of writing, there is currently an issue with adopting UniFi Access Points across multiple subnets. As a result, we have adopted our UniFi Access Points with the Controller above on the same layer2 subnet before relocating the Access Points to different subnets.

Basic MikroTik Router Configuration Example

# Configure WAN Interface:
/ip dhcp-client
add disabled=no interface=ether1
# Configure DNS:
/ip dns
set allow-remote-requests=yes servers=,
# Configure IP Addresses for each subnet:
/ip address
add address= interface=ether2
add address= interface=ether3
add address= interface=ether4
# Setup DHCP Servers for each network:
/ip pool
add name=dhcp_pool1 ranges=
add name=dhcp_pool2 ranges=
add name=dhcp_pool3 ranges=
/ip dhcp-server
add address-pool=dhcp_pool1 disabled=no interface=ether2 name=dhcp1
add address-pool=dhcp_pool2 disabled=no interface=ether3 name=dhcp2
add address-pool=dhcp_pool3 disabled=no interface=ether4 name=dhcp3
/ip dhcp-server network
add address= dns-server= gateway=
add address= dns-server= gateway=
add address= dns-server= gateway=
# Configure NAT to allow all networks to access the internet:
/ip firewall nat
add action=masquerade chain=srcnat out-interface=ether1

Configure DHCP Option 43 allow UniFi Access Points on other subnets to find the UniFi Controller's IP Address:
Note: The Value is divided into 3 (01=suboption), (04=length of payload - this must be 4), (C0A8030A= - Controller IP Address converted to HEX).

/ip dhcp-server option
add code=43 name=unifi value=0x0104C0A8030A
/ip dhcp-server network
set 0,1,2 dhcp-option=unifi

You can now relocate your UniFi Access Points to there destined subnets. They should now connect to the controller and are now ready for Layer3 management.

For more information please visit the Ubiquiti UniFi FAQ page here.