Hi!
Because of the different ONT's being in isolation from OLT, 2 methods can solve this kind of requirements:
Method 1: enabling the proxy ARP in the service VLAN.
huawei(config)#arp proxy enable
huawei(config)#interface vlanif 300
huawei(config-if-vlanif300)#arp proxy enable
huawei(config-if-vlanif300)#quit
Method 2: enabling layer 2 communication for the service VLAN.
huawei(config)#vlan service-profile profile-id 1
huawei(config-vlan-srvprof-1)#user-bridging enable
huawei(config-vlan-srvprof-1)#commit
huawei(config-vlan-srvprof-1)#quit
huawei(config)#vlan bind service-profile 300 profile-id 1