[hatch_q]

For obscurity (and some security) reasons.

My ISP supports ipv6 and i have it configured - however their software on the router/AP is bad and does not allow setting up a firewall for ipv6. This is inherent with ipv4 NAT (with uPnP disabled). So it forced me to use my own router - still the interface for ipv6 firewall is non-existent, but at least i can write firewall rules manually.

Why do I need firewall on router? Because devices on my network have services open on all interfaces - For example "smart" weather station has web service open for all to see. This is absolutely non-issue when only using ipv4 behind NAT.

Another issue is revealing of internal network topology to outside world - this is something that NAT hides really well.