BCP bridging more than 1 client not working

I need to connect three offices in same broadcast domain. I have x86 based PC with RouterOS 4.17 in main office and RB750 with RouterOS 6.4 in branches. Settings based on this article http://wiki.mikrotik.com/wiki/Manual:BCP_bridging_(PPP_tunnel_bridging), x86 acts as server.
When I connect one RB750 all ok. But when I connect second RB750, bridge on x86 don’t forward packets. List of monitored bridge ports:

[admin@Jackal] > interface bridge port print    
Flags: X - disabled, I - inactive, D - dynamic 
 #    INTERFACE                                           BRIDGE                                          PRIORITY PATH-COST  HORIZON   
 0    lan                                                 bridge_local                                    0x80     10         none      
 1  D (unknown)                                           bridge_local                                    0x80     10         none      
 2  D (unknown)                                           bridge_local                                    0x80     10         none      
[admin@Mikrotik] > interface bridge port monitor 0
               status: in-bridge
          port-number: 1
                 role: designated-port
            edge-port: yes
  edge-port-discovery: yes
  point-to-point-port: no
         external-fdb: no
         sending-rstp: yes
             learning: yes
           forwarding: yes

[admin@Mikrotik] > interface bridge port monitor 1
               status: in-bridge
          port-number: 3
                 role: designated-port
            edge-port: no
  edge-port-discovery: no
  point-to-point-port: yes
         external-fdb: no
         sending-rstp: yes
             learning: no
           forwarding: no

[admin@Mikrotik] > interface bridge port monitor 2
                  status: in-bridge
             port-number: 2
                    role: root-port
               edge-port: no
     edge-port-discovery: no
     point-to-point-port: yes
            external-fdb: no
            sending-rstp: yes
                learning: yes
              forwarding: yes
          root-path-cost: 10
       designated-bridge: 0x8000.00:0C:42:82:FF:10
         designated-cost: 0
  designated-port-number: 2

Thanks for advice!