Grpc connection failed, how to debug from listener/route/cluster/endpoint?

I got a problem when trying to connect a GRPC server from a GRPC client.
Without istio sidecar, the connection works well, but with the sidecar, connection always failed.

Error shows as following:
“2020/09/25 04:12:11 could not greet: rpc error: code = Internal desc = server closed the stream without sending trailers”

The service portname of GRPC-server is “grpc-50052”.
I can also shows configuration of listener/route/cluster/endpoint later if someone needs them.

Istio version is 1.6.10.
The connection was fine in previous versions.

So did I misconfigure something somewhere? How do I debug this problem with listener/route/cluster/endpoint configuration? Are there some documents?

Urgently need help, thank you all…