I’m aware most ISPs do not allow for port 25 to be open for email use outside of business licenses, but at what level is that controlled? Can I get around that by owning my own router? Owning my own modem or ONT? Or is this just a thing they mystically control further up the pipeline that a relative layman such as myself can’t get around?
Well, I can say that T-Mobile 5G Home Internet completely blocks all incoming port traffic.
So, you have to get creative with stuff like WireGuard & Cloudflare tunnels to do some stuff properly.