I have four AC1500 wireless routers running on easy mesh with ethernet backhaul.  They were stable for a week with all units using the ethernet backhaul instead of wireless backhaul even after reboot.  Then one of the satellites reverted to wireless backhaul and refuses to use the ethernet backhaul.  The wireless backhaul link is good but not great - 2 bars.  I have tried the following in this order: disconnecting and reconnecting the ethernet backhaul cable;  Rebooting the satellite; removing and adding the satellite again from the EasyMesh configuration.  None of this has done any good.  

The Main Router is an AX1500(US), Ver 1.26, Firmware 1.3.10 Build 20240130 Rel. 77367

The problem Satellite is an AX1500(US), ver 2.6, Firmware 1.3.10 Build 20240130 Rel. 77367

The other Satellites are both AX 1500, Ver 2.6, Firmware 1.3.10 Build 20240130 Rel. 77367

All Satellites are fed from a TP-Link TL-SG1005P, Ver 5.6 switch.  The uplink is 1 Gbs fiber using Ubiquiti media converters to convert from copper to fiber.  All other devices on the uplink show no degradation in measured ethernet performance.

I have an application which is extremely sensitive to jitter and it will not run when the uplink is wireless.