Currently they have problems with the voice between ISS and Dragon. There is a huge interference and they can't read it. Funny enough we the viewers hear it loud and clear
What got me, was that the whole boarding process was held up for over 30 minutes, because NASA couldn't progress past their 'hard wire' item on their checklist.
They eventually switched to RF (radio) direct link between the ISS and Dragon to be able to progress past that checklist item - later on the hard wire audio was fixed and working.