Temporary congestion on wireless mesh networks is often encountered. The robustness of connections is a critical issue in wireless mesh network. Rate reduction is the general way to mitigate congestion nowadays. In this paper, a new approach called as Path-alternation-based throughput regulator (PATR) is proposed to improve the robustness of TCP connections. In the proposed PATR, a Region-established M-RMAODV is derived for multipath construction. Then Rate-based Congestion Detection discovers the connection congestion. Mesh pathalternation determines a reliable path-choosing and pathswitching during congestion period. Both grid and random topologies are designed to verify the performance of PATR. From simulation results, PATR dramatically improves the throughput of TCP connections and supplies a reliable transmission in wireless mesh networks.