Metamask integration with Quarkchain devnet is failing

I was following Quarkchain developer tutorial at link - https://developers.quarkchain.io/#quarkchain-web3-js. It suggests as below

As an optional step, you can add our JRPC endpoint, http://jrpc.devnet.quarkchain.io:38391, as a “Custom RPC” endpoint in MetaMask so that MetaMask will show your proper QKC token balance.

But when I proceed to do that on Google Chrome 91 with Metamask (9.7.0), I get error as “Could not fetch chain ID. Is your RPC URL Correct”? Attaching screenshot. Kindly guide.