mikrotik rb750 with two modem e two connection pppoe client

hi
i have connect two modem to rb750 to eth1 and eth2 e created two pppoe connection…
on eth3 connect pc with ip 192.168.1.0/24 and use modem connect on eth1
on eth4 connect pc with ip 192.168.2.0/24 and use modem connect on eth2

on eth3 use dhcp server
on eth4 use dhcp server

the pc connect on eth3 surf internet
the pc connect on eth4 not surf internet
help
thank you

Max