I don’t think you need a new rope at all. I used to use one of those beaded school ropes and was able to learn DU with it. Some things that can make a difference is how far apart your legs are. I find the closer your legs and ankles to eachother the easier the DU is. Your body should also be like a straight line.
I remember I was only able to do somewhere around the 40’s on my DU until I started to put my feet together, then it increased in big strides. Other then that, keep up the practice and always research and study.
i don’t know if pressing my feet together was the “answer” but today i tried it and i finally strung a bunch together: 24, 10, 17, 14, 18, 28,10, and then 50!!
thanks for helping