Tor clients which use one-hop paths to access relays chosen by other clients can't use ReachableAddresses (or similar options) or ClientUseIPv4 0 (legacy/trac#17840). If they did, this would deny them access to some relays, potentially impairing functionality or performance. This affects the following Tor modes: * Tor2Web - Introduction Points * RSOS - Rendezvous Points For directory, guard, and bridge connections, clients choose or are configured with accessible relays based on ReachableAddresses / ClientUseIPv4/ClientUseIPv6.