I just purchased the Eero Pro 6E and Eero Outdoor 7. All my devices are working, but when I am connected to Home Asisstant on my phone thru the WIFI connection, i am unable to connect to the HA app. When I turn off WIFI on my phone, I am able to successfully connect to the app.
I bet the router is isolating your wifi from the regular network.
Basically you are on a guest network not a main network. So it is operating as expected.
There have been some issues with Eero device back an year or so.
I think the firmware was buggy and a new one was released, but I might remember the fix wrongly.
Try to update your Eero devices first and if that does not work then search for those posts.