@David-TP The firmware on that download page says it is for the X50 rather than the X55. I am reluctant to update the firmware like this in case it renders my Deco units inoperable. I did change the...

My downstairs cable TV box is connected via Ethernet to a Deco unit in the Hallway. An Ethernet backhaul runs from that Deco to a second one in the Study, and finally the main Deco in the Bedroom....

@Marvin_S I have made sure the Deco app is up to date from the Apple App Store. I'm currently using version 3.9.50 on an iPhone SE (2022). I submitted the network logs through the app as instructed.

I have a Deco network consisting of three identical X55s with Ethernet backhaul. I notice there are options in the app to set up things like Device Isolation and Connection Preference for each...