This question is the N-th number of points Ubiquti. Customers now receive addresses from the main DHCP server (on windows server, the role of the border router acts as a machine with routeros). There was a need to distribute wifi. Did the following:
In the controller settings of the access points have created an additional network with vlan 300 (for example).
On routeros on the interface looking in a local network, created a new vlan interface (also 300) and hang it on the dhcp server.
The problem is that clients do not receive addresses. Prompt where to dig and how to diagnose where the problem is?