Pixhawk 6x telem2 telem3 not showing

I have Pixhawk 6x connected to my laptop via TTL to USB converter I am using QGC V4.4.4
I have 3 telem port telem1 telem2 telem3 . but when I check paramter list in QGC telem2 telem3 are not showing I am using Firmware PX4 1.15.4 uploaded via QGC