unable to route traffic

Hello folks,
i was encountering a very strange (to me..) behaviour on my RB450G (latest 6.36rc40 firmware).

WAN port connected to a 192.168.1.0/24 network (where is the VDSL modem)
over the WAN port i make a pppoE connection
LAN1,2,3,4 (master-slave-slave-slave) and is on 10.10.10.0/24 network

if i try, from LAN1(2/3/4) to ping/http to a client over the 192.168.1.0 network it will not answer.
the only way i have to make them communicate is to masquerade the traffic out of the WAN port.
I still think that is not right… because, it is a router ? doesn’t it ?

this is the printout of my interfaces, ip/address and ip/routes

[admin@MikroTik] /interface> print
Flags: D - dynamic, X - disabled, R - running, S - slave 
 #     NAME                                TYPE       ACTUAL-MTU L2MTU  MAX-L2MTU
 0  R  lan1                                ether            1500  1520       1520
 1   S lan2                                ether            1500  1520       1520
 2   S lan3                                ether            1500  1520       1520
 3  RS lan4                                ether            1500  1520       1520
 4  R  wan                                 ether            1500  1520       1520
 5  R  ;;; TIM Fibra 100
       Fibra100                            pppoe-out        1480



[admin@MikroTik] /interface> print
Flags: D - dynamic, X - disabled, R - running, S - slave 
 #     NAME                                TYPE       ACTUAL-MTU L2MTU  MAX-L2MTU
 0  R  lan1                                ether            1500  1520       1520
 1   S lan2                                ether            1500  1520       1520
 2   S lan3                                ether            1500  1520       1520
 3  RS lan4                                ether            1500  1520       1520
 4  R  wan                                 ether            1500  1520       1520
 5  R  ;;; TIM Fibra 100
       Fibra100                            pppoe-out        1480



[admin@MikroTik] /ip route> print
Flags: X - disabled, A - active, D - dynamic, C - connect, S - static, r - rip, b - bgp, o - ospf, m - mme, 
B - blackhole, U - unreachable, P - prohibit 
 #      DST-ADDRESS        PREF-SRC        GATEWAY            DISTANCE
 0 A S  0.0.0.0/0                          Fibra100                  1
 1 ADC  10.10.10.0/24      10.10.10.1      lan1                      0
 2 ADC  192.168.1.0/24     192.168.1.2     wan                       0
 3 ADC  192.168.100.1/32   79.44.191.227   Fibra100                  0

and right now is working with that ip/nat rule

[admin@MikroTik] /ip firewall nat> print
Flags: X - disabled, I - invalid, D - dynamic 
 0    ;;; masq traffic from WAN interface
      chain=srcnat action=masquerade dst-address=192.168.1.0/24 out-interface=wan log=no log-prefix="" 

can you explain my why ?
Thanks