@David-TP Installing the beta firmware (X50-4G V1 20230831 rel 42115) fixed the problem. Thanks! Just for completeness, here's my network setup. (There are no switches): X50-4G --- cable --- X50 #1...

I have a new, Deco X50-4G working in router mode using a 4G Sim. I've then got 3 X50 mesh units connected to it either wirelessly or with ethernet backhaul. Standard wifi network works fine across...