There seem to be some problems indeed, not sure what the issue is. 17:28 has also been cancelled.

The train leaving Amsterdam at 18:28 is run by the rolling stock that is already in Amsterdam, so it should run if there's staff. There's also a train coming from Brussels, arriving in Amsterdam at  17:35. that rolling stock should normally return at 19:28. Next one is 20:28; the last direct train leaves at 21:28. It would be quite strange if none of them run.

It probably also a good idea to go already to Rotterdam or Breda (there are frequent fast trains), since I see some trains are only cancelled partially.

Thank you for the reply. The lady at the international ticket stand at the Amsterdam station recommended that we take the train tomorrow morning and we therefore we already booked the seat reservations. We now already have a place to stay in Amsterdam tonight whereas we would have to pay extra if we were to go to brussels tonight.

Additionally, it's not clear to me what your planned destination of today was. Brussels or London?

In case it is London: that can still be reached. There's a Eurostar leaving Amsterdam at 18:07, so go speak to staff NOW.

If they can't get you on that Eurostar, then they MUST help you with onward travel without extra costs and any accommodation for the night, also without extra costs. They're not allowed to say that Interrail should take care of it, since it's the duty of the local operator to help stranded and delayed passengers.

Edit: the above of course only applies if you already had a reservation for London. If you only bought that today, then it becomes a bit different. Also, it is generally a good idea only to activate a travel day when you're sure you're going to use it, since you can't cancel it when it has already started. Customer service can, but that's a hassle.