On RouterBOARD 112 I want to have two clients with two different networks, on one ethernet port.

The goal is to have two networks on one ethernet port.
MT AP--->wlan1---MTStation---ether1--->SW--->192.168.10.1, 192.168.11.1

I have tried to solve that with two vlan interfaces with different ID, than I put both in bridge with ether1 and add address to them. The problem is that after a while ping stop working, and start again after a short period of time, is the problem with ARP? Help!

Bridging is not part of the vlan process. Just create the VLANs, specifying the underlying interface when you create them. Then set the IPs on the vlan interfaces. It'd probably be cheaper to have an rb532 than a 112 and a switch capable of untagging vlans