You will probably find the SH2ac is no different in your case.
However, your theory of switching your SH2 to modem mode only mode, would be a start. The problem you are encountering is the same as most people are on VM and other ISP's - the XBOX ONE was designed and developed in the USA and used on US routers, cable modems, etc. It was not designed for UK use, but there are routers you can purchase in the UK that will get your XBOX ONE online without any 'drop-outs'. There used to be an updated list on XBOX.com website, but the guy that was doing it, has not been around for awhile now.
I would suggest you read my post on these forums which I did for another guy with similar problems. After doing so, the compatibility issues you have between the VM SH2 and the XBOX ONE will no longer be present. It took me ages to fix mine, but with that setup I can run 2 x XBOX ONE's and a XBOX 360 with no issues at all. If you have a problem let me know, and I will go over the settings which are basically default anyway.
Please read this post which was also stated as the answer!