@PitaJ What kind of reverse proxy configuration issue may it be? I've tried to change some nginx configuration lines, but withou result.
Oh I forget, I have used certbot to install SSL for my NodeBB forum, it changes some configuration in the nginx file. I do it according to this: https://medium.com/@hariomvashisth/free-https-within-5-minutes-5b67479849fa
How To Set Up Let's Encrypt with Nginx Server Blocks on Ubuntu 16.04 | DigitalOcean
In this tutorial, you will use Certbot to obtain a free SSL certificate for Nginx on Ubuntu 16.04 and set up your certificate to renew automatically. This tutorial will use a separate Nginx server block file to maintain the default file as a fallback
I notice that on the mobile safari browser, after click the 'go' button, the url seems to stop for 1 or 2 times, maybe caused by http/https transformation. But not very clear, any idea? Thanks!