dhcp-relay on one interface only

Since you changed the network 192.168.3.x (which in the example was connected to VLAN 3) DO NOT be tempted, now that you have 192.168.1.x to use VLAN 1 (use any other number BUT 1), in case of doubt, check the first few Rules of the Mikrotik Club :wink: :
http://forum.mikrotik.com/t/the-twelve-rules-of-mikrotik-club/182164/1