This read-write true/false object controls whether upstream traffic received from this specific ComPort is forwarded back downstream to other devices, and per the description true (the default) means such traffic is NOT forwarded downstream and instead goes only out the WAN interface; the description also flags this logic is reversed compared to the VLAN-group equivalent attribute. An admin uses this to prevent one subscriber's device from being able to communicate directly with other devices on the same segment. For example, an admin verifies hcxStuDnstrmFwdCntrl remains true on residential ComPorts to stop peer-to-peer traffic between neighboring subscribers' devices.