Fix Remote SSH Access

I have a physical Ubuntu server running smoothly on my local network. It holds a static LAN IP and I can SSH into it from any device inside the house, so the daemon itself is healthy.

The snag appears once I leave the building: from an outside network the connection times-out.
• Topology: one consumer-grade router between the server and the ISP.
• Port-forwarding: already mapped (router’s WAN ► 22/TCP ► server).
• Router-side firewall: I’m unsure whether it still blocks the traffic or if my ISP is adding another layer such as CG-NAT.

I need you to jump in, identify the exact choke-point, and make remote SSH possible. That may involve inspecting UFW/iptables on the server, double-checking the NAT rule, tweaking the router’s firewall, running nmap from outside, or advising on an alternate port or DDNS if the ISP is filtering.

Deliverables (acceptance criteria)
1. I can successfully SSH to the server from a device on a different network using my public IP or DDNS hostname.
2. A short note outlining the steps you took so I can repeat or reverse them later if needed.

You’re free to use whichever diagnostics you prefer—ssh, netstat, nmap, traceroute, etc.—as long as the outcome is a reliable, externally reachable SSH service.