It's hard to make further suggestions without being able to play with your router directly and see exactly what settings are enabled and disabled, or getting a packet capture to see what's happening. Lilotimz's suggestion is probably your best bet for now. Sent from my Pixel 3 XL using Tapatalk
Factory reset your Eero and redo everything from the ground up is what I'll say.
Something about the eeros current configuration is blocking the A4 and just doing these Config edits are not helping much.
So factory reset it to the basics and make sure the A4 works with that. Then slowly add custom settings and rules while ensuring the A4 is operational.
Sent from my Pixel 3 using Tapatalk