B1160 Interesting Port Forwarding Behavior 5268AC/ASUS Combination

I was confirming for another user my port forward configuration for my dual-router configuration of an AT&T 5268AC gateway connected to my ASUS router that I use for LAN and WiFi purposes. I have a port forwarding rule configured on both devices, with the 5268AC pointing to the ASUS router, and the ASUS router pointing to my Roon Core. I am on Build 1160 of my Core and Build 84 of ARC.

The interesting behavior is that I had my 5268AC custom port forwarding rule active, but the rule was not active on my ASUS router, ARC showed it was working in the Settings → Roon ARC tab, and ARC worked perfectly. I tested if ARC continued functioning with the ASUS port forwarding rule active and ARC remained working, turned off the PF rule on the ASUS, and ARC continued working.

This is a first for me, and I’m not sure if this is something unique to ASUS routers, but wanted to pass this along to the devs.