@Hille 

Admin should will have something like below.   Network NR5G and 5G band starting with N.

  @Hille Thank you for all the answers and recommendations. I apologize for my long silence, which was due to the fact that the continued investigation made me suspect that the problems were not related to the router settings, but only now has everything been clarified.
The reason for my previous question was that I did not feel that I had a 5G connection, but that both my internet provider and the supplier/installer of the antenna questioned that all the settings in the router were correct. I was also asked to test with another router, but the result was the same as with my Archer NX200.
Only after a month did my Scandinavian provider Tre check its own settings. I have been a 4G customer with them for eleven years and apparently no one there had been employed long enough to understand that the settings made then prevented access to 5G today.
After I finally got access to 5G, it turned out that I got a stronger signal without an external antenna than with it. Eventually, the antenna installer realized that the 12 m long extension cable between the antenna and the router that was installed for 4G eleven years ago causes a major signal loss when it is instead used for 5G.
Therefore, I have now moved the router up to the attic and connected it directly to the roof antenna cables. The result has been excellent 5G reception.
However, this brings me to a new question. I have had two devices in the living room connected to Ethernet ports on the router. Is there a repeater with more than one Ethernet port? Or do I need to get a repeater for each even if the devices are next to each other? And then I need a repeater for outdoor use, but one like that is probably easier to find.