Comment by gatio

> Perhaps there is also "firewalling" on the router and the phone can't even have incoming connections. Not sure.

Correct. Every home wifi router worth its salt will firewall incoming connections by default, whether v4 or v6. It's then possible (unless it's some shitty ISP-provided locked down device) to add specific allow rules, or allow all for a particular client.

egress is typically wide open, although sometimes they lock down particular protocols by default (eg. smtp, bittorrent)