@Gryphoncall66 Do you mean that the main Deco is connected to the Fios box via wifi extenders, and that it stops working when you change the Operational Mode of the Deco?

  @yves_b yes that's correct

  @Gryphoncall66 What if you connect the main Deco, in AP mode, directly to the Fios box by cable?

  @yves_b yup it works when connected to the main Fios router but doesn't work connected to either of the extenders unless the deco is in router mode. 

Also worth noting is when connected to the extenders even when the deco light is solid red the Lan port on the extender is flashing green. 

  @Gryphoncall66 When connected in AP mode to the extender, does the Deco obtain a WAN IP address?

  @yves_b it's not listed anywhere that I can find all it's showing is the Lan IP.

Oddly enough it's showing (In AP mode) 3 other devices just labeled "network device" despite the fact that the only device connected to the network is my pc so I have to assume these are the 3 other routers in my home

  @Gryphoncall66 The WAN IP should be visible in "Internet Connection".

All your routers provide access to Internet? 

Could it be that the Deco receives an IP address from an unexpected DHCP server and that this IP address does not allow accessing Internet?

  @yves_b I should not have written "WAN IP".  I should have written "IP address received by the Deco from a DHCP server".

  @yves_b Only one router has a direct Wan connection the other 2 are connected to it.

In Router mode I see the "internet connection" setting but it does not exist in AP mode. Even in router mode the only thing I can find is that it says it's a dynamic IP (Pic attached) 

  @Gryphoncall66 In AP mode (via the extender), does the Deco also receive an IP address in the 192.168.1 range?