My ISP puts everyone behind some sort of NAT, which means I can't reach my home network from elsewhere since I can't open ports. They'd let me buy my own IP address for a monthly fee, but I've found that an old Pi I already had, an autossh-ed reverse shell, SSH forwarding and a cheap cloud instance work just fine for checking sensors and the like, cost less and the cloud instance has other uses, too.

I see, so NAT traversal over SSH as opposed to VPN/DDNS