My AiMesh setup:
AC5300, FW: 3.0.0.4.384.32799, Parent
AC5300, 3.0.0.4.384.32799, Node 1, ethernet to Parent. Connection Priority set to Ethernet.
AC5300, 3.0.0.4.384.32799, Node 2, ethernet to Parent. Connection Priority set to Ethernet.
Backhaul Connection (Priority: "Ethernet", Type: "Wired"), Gigabit Switch between Router to Nodes, ISP: Comcast Gigabit Pro (Fiber: 1 Gbps up/dn)