This sets the inclusive lower bound of a transport-layer source or destination port range to be matched by a filter using this group, and it must be less than or equal to the corresponding cfgFilterIpServicePortHigh value in the same entry. This range-based approach lets one filter entry cover an entire block of ports, say an application's full ephemeral range, rather than requiring a separate entry per individual port number, which matters for keeping filter group configuration manageable for services that use wide port ranges. A filter entry intended to match an entire range of ports used by a VoIP application's RTP streams, say 16384 through 32767, would set this object to 16384 as the range's lower bound.