建议对 IPv6 进行抽样，略过最后 4 个段，以避免同一个子网无效测速。

Function requirements According to the IPv6 specification, a /64 subnet (the last 4 segments, each 8 bytes) is the standard second-layer network boundary. IP addresses within the same /64 share the same external routing node. In other words, /64 must be on the same physical line, and it makes little sense to extract multiple IP addresses for testing. Currently, if a /64 segment is entered, the program will extract about 100 IP addresses for repeated testing. However, it is enough to extract only one /64.