@KnobbyVas 

I would consider looking into getting something like opnsense or pfsense before paying for a router supplied paid security service or replacing one to get a non paid security service. 

So it seems that there are a few options if you have 1Gb or so fibre to your home and have an Homecare setup (e.g. appropriate hardware versions of M9/M5 or X20/60)

However there do seem to be some workarounds, based on keeping the HomeCare device as the main router e.g.

• Keep the Homecare device as the main device on the network and the main router and connect to the newer Homeshield devices with either
  • Putting up with the 5Ghz Wi-fi backhaul at around 867Mb/s (does it make much difference?)
  • Use ethernet backhaul and get full 1Gb/s

It appears that adding a homeshield device as a node doesn't affect the HomeCare service as long as the HomeCare device is the router.

Obviously, anything above 1Gb/s internet connection is going to require you to get a router with at least 2.5Gb/s network ports anyway, so you are stuck with Homeshield there