GRPC closes unexpectedly

Hey everyone,
I’m using Cloudflare to connect to my proxy server in origin. I’m using v2fly as a proxy server. it supports lots of network protocols for connection e.g. ws, TCP, grpc, and …
unfortunately, I couldn’t set up any of the except grpc and ws to be used behind cloudflare DNS reverse proxy (on port 443). ws works just fine behind Cloudflare. but grpc connection just works for about 30-40 seconds and then closes unexpectedly. while it works perfectly when I disable cloudflare proxy and directly connect to origin.

I Believe the requirements are as follows:

  1. HTTPS
  2. Full (Strict) SSL at SSL/TLS tab of Cloudflare dashboard
  3. With :orange: (proxied) port has to me supported and compatible
  4. gRPC feature has to be enabled at Cloudflare dashboard, navigate to Network → gRPC

Could you re-check if you have all of them?

If using HTTPS, you should be using WSS.
Same as above bullets about HTTPS, SSL and port.
Also make sure WebSockets feature is enabled at Cloudflare dashboard.

Ports list compatible and supported when using :orange: cloud (proxy mode) on Cloudflare can be found here:

May I ask what SSL option have you got selected under the SSL/TLS tab at Cloudflare dashboard for your domain ( Flexible, Full, Full Strict … )?

Here is a way to re-check if you correctly setup the SSL for your domain with Cloudflare:

Last but not least, kindly have a look here for more information regarding correct SSL settings at the SSL/TLS tab on Cloudflare dashboard:

1 Like

hey fritex,

I have all of them.

I don’t have any issue with wss. it works just fine. I’m having issues when using grpc as a transfer protocol. my connection to proxy server issues successfully and I don’t any issue surfing the internet with that. the problem shows up for example when I’m downloading a large file in which that single connection used for downloading closes after 30-40 seconds and downloading fails. i think it’s a sort of bug in Cloudflare grpc support.

I’m using full strict and I have set up my reverse proxy server on origin appropriately with my Cloudflare private key.

May I ask what is the size of it?

You are using a Free or a Paid Cloudflare plan?

size doesn’t really matter. it can be anything between 100MB to 100GB. if it takes more than 40 seconds, the issue comes in.
I’m using free plan

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