Proxied gRPC bizarre issue

[ping-lin.chang]

When we turn on the proxy for a A record DNS (orange-cloud) as suggested by the Cloudflare official tutorial “Understanding Cloudflare gRPC support”, the GRPC client always reports an internal error with a description of “server closed the stream without sending trailers”.

However, when we disable the proxy (gray-cloud DNS only), everything works fine.

Cluelessly enough, if we create a gray-cloud CNAME record pointing to an A record for the origin gRPC server (behind GCP HTTP/2 LB) in orange-cloud, everything works fine again.

Any help would be greatly appreciated.

[ping-lin.chang]

Related issues:

GRPC & HTTP Proxy

Is it possible to turn on HTTP Proxy on a domain and still use a GRPC protocol towards that domain? Background: I have a website on mydomain.com/ and a GRPC API on mydomain.com/someApi. When I turn on HTTP Proxy for the domain the GRPC client (outside mydomain) always returns an Internal error (when trying to reach mydomain) with a description of “server closed the stream without sending trailers”. PS. When turning off HTTP Proxy and use CF for DNS only, everything works fine. Any ideas?