Site took too long to respond error message implies that there is not response received from your server. In case Webmin is running most probable cause to this is your firewall blocking port 10000.
Try running the following command to open needed ports on your Ubuntu instance:
We are glad it works for you, as based on the screenshot you shared few days earlier on one of the deleted posts (as administrator I could see it), which contained your system’s IP address, and checking your IP:10000 seems to work fine for me today, presumably after firewall ports were opened.
… based on the publicly shared screenshots, with wiped off hostname (with red brush, when you were running systemctl status webmin) your hostname doesn’t seem to be set to FQDN (as it is just too short).
For production systems, it’s suggested to have hostname be set to FQDN, using hostnamectl command.
@Ilia Yes, it is actually working now, thank you, but as @calport mentioned earlier this could “potentially” issues in the future as WordPress supposed to be installed on a fresh OS, as unfortunately, I come to know about Virtualmin after, now I can only backup my site and re-start again