Today, I managed to keep an SSH session alive between restarts

I run Debian 9 on VirtualBox on a Windows 10 host. I happen to live in an area with seasonally chronic network shenanigans, so every now and then, I have to Avada Kedavra (tilde-dot) my broken SSH sessions, but I witnessed this weird one today.

I hibernated the host, turned off my phone's hotspot and went for a walk. I dehibernated to Windows' lockscreen 2 hours (give or take) later, but I still wasn't hyped about refactoring, so I left it at the lockscreen. After some 45-ish minutes of funny YouTube, I ditched the bed for my workspace again. This time, I pushed past the lockscreen, manually reconnected Windows to my phone's hotspot and made for the VM, where I met a seemingly dead SSH session. I typed in a command and hit return with a shrug, but it actually spat out appropriate results. After about 3 internal WTFs, I ran more commands, just to make absolute sure I was on the remote machine.

I'm still on the the immortal session, with all but one question for y'all who actually know their RJ45s...

How?