I was recently stuck in Brussels overnight when my DB ICE train from Germany was cancelled. DB did eventually get me to Brussels, but it wasn't in time to make my Eurostar connection to London. This meant I had to pay for a hotel for the night, because there were no more trains to London that evening. HOTNAT meant Eurostar put me on a train in the morning without needing to buy a new ticket.
It's not possible to buy a through ticket for my whole journey, so the DB section and the Eurostar were separate tickets - which doesn't matter for HOTNAT. But if the whole thing had been one ticket, DB would be obliged to pay for the overnight accommodation. I can definitely get some delay compensation from DB, but am I entitled to any refund from DB for the extra expenses?
(I probably have to ask regardless so that I can try my insurance if not, but it would be good to have an idea what to expect)