Webmail on a simple managed / shared host.

After a permanent crash on another large host, I started migrating to a new host. My previous two hosts were Windows-based (essential elements such as MSSQL), but I put the main site offline until we completely reworked it. I've migrated to a basic shared host. At the moment, all I need is to access a few simple pages on about 5 different domains, as well as a reliable email. I hardly use the installed applications, but I could do it in the future. No CMS although I can look for 2 different areas.

However, I am currently experiencing a problem using CPanel which, I ask, is inherent to this system. On previous hosts, I had no problem staying connected to the control panel (usually Plesk) or to an email. I'm connected to various networks (usually at home, in the office, and on mobile) and these networks are changing the public IP address – which I can not change because it's at the enterprise level (most of my sites and e-mail addresses are essentially personal). Email does not stay connected on Roundcube for more than 2 minutes on the corporate network and 5 minutes on the home network. The host control panel expires quickly – I completely lost tickets that I spent time writing, but at the time of submission, they were lost when I was brought back to a login screen.

My current host tells me that there is nothing to be done about it since it is CPanel. Is it true? Is it better to go back to a Windows host? I need a webmail because I use about 5 different devices.

Any other ideas?

WHT looks great – I would like to have found this a few months ago or earlier!