Can't connect to server issues?

I seem to be having issues connecting to my websites and email. If I tether my phone to my computer I get https://xxxx.com:10000/firewall/?xnavigation=1 when trying to access the control panel and when trying to visit the website I just get can’t connect to the server. Where do I start looking for the problem? I assume the Linux Firewall but what should I look for?

Your intro with OS and Webmin/Virtualmin Versions are missing, so we don’t know at wich OS or version you work!
Can you login to your server via SSH? Then login, deactivate the Firewall and see, if you can access the Webmin-Port 10000 afterwards.