Webmin
I don't bother to use Webmin, it has been well over a year since I tried to use.
I am a bit lazy sometimes and use Webmin to help setup certain services, e.g. Samba. Webmin is a web interfaced system administration system for Linux and has lots of plugins for various Linux apps/packages. Webmin has its own mini webserver built in. There are lots of web page discussing Webmin, how to install and use, e.g. How To Install Webmin on Ubuntu 18.04. To date I have only used Webmin on my main home server, not any of the virtual machines or router.
A key difficulty I have had recently is that most the modern web browsers no longer seem to allow self signed SSL certificate exceptions. Fortunately as I only wish to run Webmin locally (LAN), not facing the public internet (WAN), I can still access locally without SSL setup (http not https). To do this from the CLI as follows: sudo vim /etc/webmin/miniserv.conf, change SSL=1 to SSL=0, save and exit, then restart webmin to take affect, sudo systemctl restart webmin
I tried to reverse proxy Webmin to my main web page, but did not get the reverse proxy to function properly, so disable this feature. I do not really need or want Webmin facing the internet. This would only be another security vulnerability.
I can now relatively easily assign local web pages a local signed certificate via Traefik and my local DNS, however as I do not use Webmin there is not much point even trying at this time.