No, but Denon UK specifically asked me to try with the router disconnected from the internet (as they state that this should still work fine - i.e. the page will be still be presented) - but no, the issue persists.

It has nothing to do with the router or the internet connection - the unit cannot present the web page after a preset has been added - it really is that simple - why can I not get anybody to just test this for me - and when I say this I really mean Denon themselves ? (i.e. you or your staff if that's appropriate/possible)