None of this really seems to make sense but here we go: Pi3 Netgear Genie Nighthawk X4 R7500v2 Wireless AP Wireless just would not work right it would connect with no issues, it would ping with no issues, traceroutes to/from were ok (even TCP sync traceroutes -T) SSH connections would ask for the PW...

More updates

The double NAT issue I thought I had was a problem with my Win7 - see this KB
http://support.microsoft.com/kb/926179

My iphone works just great both via LTE and WIFI

I have not done any throughput testing but it certainly seems adequate so far (Windows RDC, SSH etc)

Ok works on IPhone but is not working through a double NAT. Need to resolve that first. I see that there is lots of information out there about double NAT issues so I am not anticipating any real problems, just more fiddly little problems.

Finally got it working. I followed this web site:

https://raymii.org/s/tutorials/IPSEC_L2 ... 12.04.html

These is still much to work out (DDNS, throughput etc) but it works! If I run into any other stumbling blocks I will post..

ipsec\l2tp