You can find the Max Network Device settings in the BP_PlayerPowerComponent in the Class Defaults find the Placement Settings category then find the Network category.

Here you can change the Max Network Device settings, you can hover your mouse over each settings name to get a tooltip with more info about each setting.

Use Max Network Devices – If true the maximum size of a network (Devices connected to each other) is capped by the Max Network Devices value.

Max Network Devices – The maximum number of devices that can be connected to each other If Use Max Network Devices is enabled.