Hello @pfaffman , thank you very much for your information! Following the instructions in that post, Discourse welcome page finally shows up.
There is only one minor issue left: I use cloudflare to generate a certificate for origin server. But when I try to access the page from the browser, it gives a NET::ERR_CERT_AUTHORITY_INVALID warning (though I can proceed by ignoring it, but my users probably don’t want to).
I’m wondering if this issue has something to do with Discourse, and is curious about the methods to actually debug this issue. Thanks.