Access router webpage securely (https) with nginx, how?

Hello All,

In my current setting (Raspberry Pi running Raspbian (Debian Stretch 9.5) and nginx/1.10.3 (installed via sudo apt-get install nginx)
nginx -v log: https://pastebin.com/RsUmkr30

I have installed SSL certificate successfully and can access my Home Assistant installation securely (SSL) and successfully.

My router allows Web Management Port so the router webpage can be accessed but non-securely.

Please, kindly help configure nginx to access the router securely. I am able to access the router webpage securely but it is not displaying as it should:

router1.png shows router webpage non securely
router2.png shows router configuration
router3.png shows router wepage securely but it is not working

/etc/nginx/sites-available/default
is in
https://pastebin.com/JYwnf8aT

# port 4321 forwards to 4322 as a test since I access port 4322 directly
# this is the SSL server. / links to Home Assistant and and /dev01 should link securely to the router

Thank you in advance for your kind support,