HELIX 7 G2N models can be networked without the AS ETH 5XPG if there are only the 2 devices (head units or Ethernet accessories)  in the network  ... Any other Ethernet device counts as 3 devices which then needs the AS ETH 5XPG  ... 
Any HELIX 7 that is not G2N cannot be networked with any connection  ... 
Rickie