I had posted before about mobile issues and virtualmin/webmin before. I thought I had the answer by re-installing from scratch, but that didn't pan out either. So, spec's first:
Webmin 1.9 Usermin 1.751 Virtualmin 6.06 CSF 12.10 Kernel & CPU Linux 3.10.0-957.12.1.el7.x86_64 on x86_64 CentOS Linux 7.6.1810
All software is up to date.
Issue: I can connect to virtualmin via home network (wired and wireless). I can connect to the websites just the same. On my Boost Mobile (don't know if it's specific or not, so why not specify right?) running Android 7.1.2 and backup running 8.1.0, I can connect to the websites just fine, however, connection to virtualmin/webmin timesout.
I have the wbt-virtual-server-mobile-theme installed. There's nothing in the /var/logs that I can find regarding this and the ip address for the phones is in the permitted list of CSF. However, I'm thinking it's more specific to the mobile network.
I have used the mobile hotspot feature of both my primary and backup phone to connect to the net via wireless. It too failed and timed out on attempting to connect to the webmin/virtualmin, but not the websites.
This does affect the ability for the phones to receive and send emails.