Firewall settings after hard reset (data loss)

Unfortunately, after performing a hard reset, I lost the firewall’s factory settings and would like to ask how to configure the rules so that they protect the internal network without significantly affecting internet speed, whilst also ensuring privacy? When it comes to firewalls, I’m unfortunately a complete novice.

My gateway to the outside world is the lte1 interface and my internal network is a LAN, bridged on bridge1.
I would be extremely grateful for any help

Understand the default router configuration first, tweak second.

Starting point would be to execute

/system/default-configuration/print

inside a really wide terminal window. You can then copy-paste relevant settings back into the terminal window to get to default setup. And default setup is as high performance as it gets.

Then it comes to modifications as per @tangent suggestion.

Standard firewall is here:
Buying - RB1100AHx4 Dude Edition - Questions about Firewall - #4 by rextended