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I discovered that the switches I was using all had "Green Ethernet" built-in and there was no way to disable it. Green Ethernet is a common name for a set of features that is designed to be environmentally friendly, and to reduce the power consumption of a device. Orbi and other routers don't like Green Ethernet, and it causes disruptions in service. So, I purchased a Netgear managed switch, which allows me to turn on or off Green Ethernet, as well as a slew of other features. So far it's working fine.