replace relative by an infinitive qualificative

[logicgate]

A.

It sounds like a german construct. Can we say instead of

Dat hangt af van het soort probleem dat opgelost moet worden.

>> Dat hangt af van het soort op te lossen probleem.

Is it natural dutch or correct at all?

B.

Regarding the first sentence with the relative proposition, what is the best word order or way to say (>"It depends on the type of problem to be solved")

1. Dat hangt af van het soort probleem dat opgelost moet worden.
2. Dat hangt af van het soort probleem dat moet opgelost worden.
3. Dat hangt af van het soort probleem dat moet worden opgelost.
4. Dat hangt af van het soort probleem dat opgelost wordt.
5. Dat hangt af van het soort probleem dat wordt opgelost.

I would say 3 and 5 with a preference for 3. It seems there are no hard rules in dutch for word order at the end of a relative, would you confirm?

[LeSNT2]

A. Yes, you can say "Dat hangt af van het soort op te lossen probleem." It's correct and also not a very strange construction.
B. I would say that number 2 is a bit strange. At least for me. Number 1 and 3 says exactly the same. Numbers 4 and 5 also say exactly the same. They do say something different though. So 1/3 and 4/5 have a different meaning.

1/3: It depends on the type of problem that must be solved.
4/5: It depends on the type of problem that will be solved.

So in the first and third sentence, the problem must be solved (but maybe there is no solution yet). In the fourth and fifth sentence the problem will be solved (there is a solution and they're working on it).

Hope this helps!