By the way, my url setting in config.json is same with url in nginx.conf .
My status quo is that
I set the url in config.json and nginx.conf as “https://mysite.top” which DNS response to my IP in LAN for intranet use.
And for users from the Internet, I do frp to map my nodebb to my vps whose IP is bound to “www.mysite.top” . So I can visit it from internet by https://www.mysite.top .