Hello, everyone!
HG8240H is bridge + voice ONT

Need to ping the default IP, when the cable is connected to LAN1. You must repeat the process for LAN2, LAN 3, and LAN4. Be sure to change the cable each time you click on the corresponding port. If all the PINGs are successful, then we're fine. If you do not have any packets after the ping, the problem is from the top level of the OLT. The ONT is layer 2, where it should be enabled by default. If it is not, it means that have a problem with OLT in which you limit your port.
Thanks.