The operator of the delayed train is responsible for secure you onward journey.
Means that they have to provide a Hotel if needed and change all reservations and tickets without any charge.

You should visit Service office of the railcompany and ask for assistance. Often they say that the European Passenger Rights are not valid for Interrail but that is wrong.

If they fail you can always ask the Eurail Serviceoffice but they work mainly just on business days https://eurail.zendesk.com/hc/en-001/requests/new

@seewulf  a problem is that VY Sverige or SJ doesn’t have any offices in Sweden only web help or call center

Basically have the same problem with the same connection, just in the other direction.

Gonna be stranded in Narvik this evening with no chance to get the bus to Tromsø.

VY and SJ aren't really careing, since they will get us to Narvik as promised (just waaaay to late) and since we haven't booked the bus connection with any of them (not even possible) they won't do anything for us.

A request for accommodation was declined.

How did all work out for you in the end?

There is still staff on the trains worstcase.

Option B is to get a delay proof  and then pay for all and afterwards reclaim the money from the company (that caused the delay) back.

@AmA Yeah it´s sometimes quite hard. Luckily i have a good travelinsurance that says (if i had a sheduled layover of atleast 2hrs) they pay for it. But i have to try first to claim the money back from the companies.

Yes, the best is to ask any rail staff what to do when you think you may miss your last connection. On-train staff will often know where you should go to get assistance.

Hey! 
Oh man.. that sounds so familliar. 
Honestly it was a hard trip for us. Both directions. On the way to Narvik, we got stuck in the train for more than 24 hours without getting even close to Narvik. After solving the problems we were so late, we stopped in Boden C and they told us we will get busses to Narvik. Suprise suprise, the busses never came and we gad go take a hotel for the night and took another train at 6 in the morning. We finally arrived in Narvik more than 24 hours late. 
 

On the way back to Stockholm as you already know our train got late, so we couldn‘t get the trains we should have get. 
We took a train much later and arrived the next morning in our home town. 
 

We‘re finally at home and are so glad to lay on our couch. But we got covid on the first train that was stuck. (Both vaccinated 3 times) So now we‘re in quarantine. How horrible can a year start? -yes!

We will try to get money back but it will take time until VY is answearing. 

If you‘re on an SJ train you can contact their Facebook Messenger. They are very nice and helped me very fast. I think VY is the problem and their costumer service. 
 

i hope you can enjoy your trip. :)

ah! I just forgot the say that all the staff on the trains were so nice and accepted the tickets from the day before. Everybody said that it‘s not our fault and can stay on the train. So glad!

That was not just being nice: the rail companies are obliged to assist you to get home without any extra costs. They were also obliged to arrange accommodation where you got stranded and to provide food and drink. You can claim back your extra costs (based on EU Regulation 1371/2007). They have to reply to your complaint within a month; if you're not satisfied with the reply (or if they don't reply within that time), then you can file a complaint with the national enforcement body. In Sweden, this would be Konsumentverket, see this page about how to file a complaint.