Hi guys,
I just wanted to update with my progress and hopefully help anyone who had the same problem as me.
I bought the Vigor 120 modem and using default settings i.e. not doing anything, it worked straight away.
I set the R7800 back to Router mode from AP mode and entered my sky username and password in the internet setup, PPPoE section in the Netgear Genie and it connected straight away.
I then proceeded to plug the Vigor 120 directly into my laptop Ethernet port to update to the latest firmware F/W 3.2.8.2 (10 April 17).
The Vigor 120 is an interesting device as it seems to run a DHCP server for configuration purposes, however when in this mode there is no access to the internet. This is because there is nowhere to enter the SKY username and password details.
Connection speed is a tad slower than the Broadcom SKY SR102. I tested this through my max download speed using my uploaded.net account which maxes my connection. SR102 achieved 1.87MB/s whilst the Vigor 120 (ADI chipset) achieved 1.73MB/s. This is not a big deal for me as I am more concerned about the LAN network and connected devices (USB3 storage and soon to be QNAP NAS).
The Vigor also seemed to have solved my windows access issues to the ReadyShare network storage drive, which was intermittent when I was using both the SR102 & HG612 as Modem and DHCP. With the R7800 handling DHCP and NAT duties it appears straight away in the Windows network finder where I have now mapped it as a network drive.
Overall, I am happy with the Vigor 120 so far, although at £55 shipped, it wasn’t a cheap option! I will be keeping the HG612 if fibre is ever rolled out in my area or I move.
Finally, wanted to say thanks to all the contributors to this post who assisted me.