Plan a conduit for Telekom?

I didn’t know that [Tiefbau + Leerrohr] was included! :-( With us, the structural engineer (=GU) has now completed everything, the company commissioned by Telekom only has to pull the fiber optic cable through the 5m long [Leerrohr]. The cable end is already exposed, the [Leerrohr] starts right there. We basically paid twice.

So I need to bring up the topic again here:

Telekom, of course, despite multiple assurances, has not managed to send out the order. Naturally, I was also not informed about this, despite assurances. On Monday, I need to have the pipe on site and now I am under pressure again. Yes, I know, it's my own fault for relying on multiple assurances from Telekom...

My neighbor simply had a 1 inch (DN 25) HDPE pipe laid as a conduit, and the supplier (not Telekom) also used it without complaint.

The Telekom hotline couldn't tell me what I should use either. Online they talk about DN75. The hotline spoke of DN 62/67.5/72 depending on how many services you have. When I look at a table of the different DN sizes, such things don't even exist...

I am now inclined to have the 1 inch HDPE pipe laid as well and see how it goes. If Telekom resists, they can forget it and I will switch to my neighbor's provider. That worked out.

Question, maybe unnecessary/wrong out of ignorance: how is it sealed in the multi-service line if it's designed for DN75 but only DN25 goes in? Isn't that problematic?

Alternative: We do nothing and Telekom has to dig everything up again. According to Puma, the first 15 meters are included and for us it's just under 12 meters.

I am really undecided right now about what the right approach is...

Buy Kabuflex DN 50 with pull wire and throw it in. Sell the rest of the roll to the next builder on eBay Classifieds.

How did that thing end back then?