GRPC closes unexpectedly

[user17032]

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.

[fritex]

@user17032

grpc

I Believe the requirements are as follows:

1. HTTPS
2. Full (Strict) SSL at SSL/TLS tab of Cloudflare dashboard
3. With (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?

@user17032

ws

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.

• navigate to Network → WebSockets

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

• https://support.cloudflare.com/hc/en-us/articles/200169156-Identifying-network-ports-compatible-with-Cloudflare-s-proxy

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:

Deprecated - Step 2: Setting up SSL with Cloudflare

This tutorial is deprecated in favour of Get started with SSL/TLS · Cloudflare SSL/TLS docs

Archive

This tutorial covers getting SSL working with Cloudflare in various different scenarios. This assumes you already have your website set up on Cloudflare with all your DNS records set to , if not - please visit <a href="https://community.cloudflare.com/t/64309">Step 1</a>. Do you want the website to use HTTPS? Yes Do you already have a valid SSL certificate installed…

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

Why you should choose Full Strict, and only Full Strict

Unencrypted & unverified connections Imagine you open Paypal and suddenly get that warning [image] Would you continue? Probably not. For decades leaders in IT security have advocated that people upgrade their sites from unencrypted HTTP to secure HTTPS. And for a reason, everything you send via an HTTP connection is sent in plain text and can be intercepted at any point between you and the server. Equally, you’d probably not proceed if you got such a warning, right? [image] That’s when th…

[user17032]

hey fritex,

@fritex

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

I have all of them.

@fritex

If using HTTPS, you should be using WSS.

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.

@fritex

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 … )?

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

[fritex]

@user17032

when I’m downloading a large file

May I ask what is the size of it?

You are using a Free or a Paid Cloudflare plan?

[user17032]

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