Multiple router network randomly freezes

I have a network with three ASUS routers. The first router A was set up as the primary connected to the ISP. This router was set up in Wireless router mode. The next two ASUS routers (B and C) were set up in AP (Access Point) mode. All had DHCP Server enabled. The routers are at least a quarter mile apart from each other. They are connected via a Ubiquiti dish network. With the ISP modem connected directly to Router A the network was working fine. We then had to move to a new ISP. They required that we install their router “D” as the primary router. Their modem/router is a Pace 5269ac. I conne

Question by Steve049 on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.