@Hank21 

Hi, yes when on same wifi it works fine. I will check ACL rules next time. I was having some strange wifi issues with this setup, constantly dropping during a teamviewer session, so I removed the hardware for now.

  @Chad711 i couldnt get mDNS working properly either, tried using the gateway for my home app cameras and also chromecast but needed also airprint to work which didnt allow me to add a AP mDNS instance when you already have a gateway instance. 

Ended up just going back to using Avahi on a ubuntu vm. Hoping dev's can update the mDNS settings so it is easier to setup and also allows better integration with apple protocols. 

  @Chad711 funny you say that cuz I had a er605 v1 sitting in the closet collecting dust. I saw that v2 had mdns so I just bought another er605 last week, swapped out my sophos for er605 only to find out mdns is bit half baked lol. I'm at a point of no return to switch back to sophos as I had to make significant changes in my environment so way too lazy to swap back lol.

so far seems to be pretty solid, had couple odd issues here and there, fw acl seems to very buggy. Like switching around priority of the rules doesn't seem to stick unless you refresh and drag and drop the rules again. 
 

had bit of a headache doing shieldsup test which was showing majority of my ports closed instead of stealth which really bothered me from a security perspective, especially moving away from a ngfw, but finally got that sorted. Was one of the attach defence setting. Had to turn off "Block TCP scan with RST". Now finally my environment is stealth!!

im gonna continue using the er605 for now and maybe when I have time, introduce the sophos inline for some additinal security. 

  @j0np So does your mdns some what work or it doesn't work at all? My wife goes into work once a month so that week she is out I will try to do this all again but each time I have tried this I ran into wifi issues. Maybe a DHCP issue. I can't seem to find a solid guide on proper AT&T router passthrough. If I find a video there is replies from ppl stating they have issues or they say you should do this/that. Hopefully I can get it all setup and working right one day!

  @Chad711 mdns was not reliable at all. When I setup the mdns gateway, some of my Chromecast and cameras worked (iOS home app), however randomly would drop. For iOS AirPrint, couldn't get that working at all using the AP mdns instance. Seems very convoluted for such a simple configuration so I gave up lol. Avahi so easy to setup and bam working beautifully
 

For gateway, I haven't been using the ISP provided router since day one, I originally used sophos instead and now er605.

funny you say that you may be having dhcp issue, i noticed today one iOS device and one of my VM's couldn't renew it's ip and dropped connection. Had to forcefully renew again and worked. So another issue to add to the list :(