5Ghz & 2.4Ghz share same password on Google mesh. Phones etc. capable of 5Ghz default connect to 5Ghz. Therefore when trying to add 2.4Ghz devices to the mesh they can't connect to the 5Ghz that the set up phone etc. Is on so the setup attempt fails. There is no way to force the mesh to temporarily default to 2.4Ghz. Google says try walking away from mesh far enough that the shorter range 5Ghz connection drops out but the longer range 2.4Ghz remains. Really! Look at other products before buying.