Comment by notepad0x90

It is not, you guys are talking from a specific american ISP perspective where you have these modem+router+gateway+firewall combo devices. Not everyone gets that.

Many get just a modem and buy a cheap router which may not have a firewall. MANY more get just a modem and their laptops are directly exposed to the internet (!!!), those you can't do much about, but many put a "router" that's just a cheap wifi access point with layer 3 routing and NAT. If you chose to "bridge" a device (like those internet exposed laptops) or port-forward, it will just work (even with ISP routers!!) there is no firewall rule change required.

I've worked in this space supporting consumer grade routers, and then worked in enterprise networking. But don't take my word for it, you all can take a trip to shodansafari, how many devices are listening port 3389 and 445 with consumer grade laptop names?

But it isn't a popular thing to say for whatever reason. I guess IPv6 is a political ideology now lol.