According to the DECT NR+ documentation, NR+ is designed for "ranges over a kilometer" between devices. The coverage is also up to 3 km as stated in comparison table for DECT NR+ and LTE. Therefore, 1-1.5 km as you mentioned between two DECT NR+ nodes is within the range but the maximum is not guaranteed by the documentation. The range depends on factors such as antenna design, environment, regulatory limits and output power meaning that in order to confirm the performance, you have to test your device .
