Battery reset first, I'd suggest. Disconnect the battery for a few minutes and then re-connect. Can solve a multitude of gremlins. Other than that, at first thought, it seems that one of the D2B linked modules is intermittently faulty Allen. The D2B loop has to be complete for the whole setup to work. I think perhaps the phone module in the boot might be a place to start. You can take any of the D2B modules out of the network loop by disconnecting the fibre optic plug and fitting a bypass loop, which is just a plug with a loop of fibre optic connected between the two terminals. Alternatively, you could have a Jaguar dealer do a diagnostic check, ,although I have to say, from experience, that I don't have that much faith in them.