iDMSS Failure to connect over cell service only

It’s technically possible to use P2P which is built into the NVR, but I don’t recommend it
why is that. everyone who installs around here uses it so it they don't have to log onto someone's router, open ports, ip changing dyns services. unless there is an easyier way then p2p, i would love to know.
 
Because it is not secure, around here everyone uses vpn. Not easier, but better. That's the way the most people around here do things.