LTE Uncapped SIM in iPad?

Hi all.

I was an early adopter for the LTE uncapped offering. I now have fibre and I am happy. I clipped the telkom SIM down to nano size and put it into my iPad. The iPad recognizes the SIM, there is full signal. I have enabled LTE and tried a variety of APNs. There is no internet connection. I think the SIM might be locked to the modem and it is not possible to use a fixed wireless SIM in an iPad. Is that correct? Is it possible to bypass this.