Ended up buying another AX55 supporting ethernet backhaul and forcing the US firmware V1_1.3.2 Build 20240325: Web UI:

Well after some days, it doesn't properly work, the wifi provided by the RE700X is not fully stable, I guess it's not effectively part of the mesh system, but simply acts as an extender with the same...

@JP_NL FWIW, I have this configuration: - ISP router - Archer AX55 (1.2.6 Build 20231130 rel.36135) - RE605X (1.1.4 Build 20230509 Rel. 78185) - RE700X (1.0.2 Build 20231129 Rel. 63661) Configured...