ssh iot device behind firewall

https://remoteiot.com/

You can directly access a Raspberry Pi located behind a firewall from any location, with the same seamless experience as if it were on your local network. Through a web portal, you can send commands and batch jobs to the Raspberry Pi effortlessly. There’s no need to manually find the IoT device’s IP address or modify any firewall configurations. This solution supports all Linux-based machines and a full range of TCP services, including SSH, VNC, RDP, and HTTP.