rust client return gRPC 'Connection timed out' when call scan_keys or batch_get api

[qwm-db]

issue detail:
thread 'CPU-worker' panicked at 'called Result::unwrap() on an Err value: Grpc(RpcFailure(RpcStatus { code: 14-UNAVAILABLE, message: "Connection timed out", details: [] }))', /home/qwm/src/fabarta-db/src/store/src/tikv/mod.rs:86:53

Rust Client timeout:
kv_timeout = 60

TiKV config:
[server]
grpc-concurrency = 4
grpc-keepalive-timeout = "10s"