Opening iptables for initial Android setup blocks connectivity

I installed an AOSP Android 12 based ROM with root. I set up a simple custom stateful iptables firewall to block all connectivity except for a browser. I connect to WiFi and there is no internet. This setup does work after some initial network activity occurs on a freshly setup ROM with just the default firewall left in place for a little time (until browser able to access internet). What sequence of events occurs behind the scenes on a freshly set up Android ROM for the internet connectivity to be enabled? What sort of things must occur for Android network connectivity to become available for apps after a fresh installation and after having established WiFi connection? There's no internet if you just open up the firewall for one app on a new installation and having connected to a WiFi.