When an ISP says "we don't support Linux" (I think) it really means "We don't know Linux".

Linux is stable. It will stay up without rebooting for months. Firefox is a dream to run.
Install scripts are much improved for different (free) programs (software other than the OS).

For a year and a half I had an old PC running Linux non stop until the hard drive gave up its ghost.

There is a learning curve if you want to understand the shell/console commands.
Much about Linux is just straight text files.

Grab a distro and install it. Then you'll know.