there are various reason for this and several solutions are available.
No. 1 rebinding
this is 1st solution by DJI customer center
https://www.youtube.com/watch?v=X7FsdCPrEeU
but for me does not work.
in my case, it is wifi extender battery problem.
i tried to replace battery. but it is hassle thing.
finally most easy solution for me is
connect external mobile lithium battery !!
easy and clear!!
good luck!
