no live video

I recently just out put in a 5.8 dbi range extender and with I came across the problem of having the live veiw of the screen on my phone being black does anyone no how to solve this issue ?

I am starting this new thread since there are a lot of people with this same error but nobody has found a fix as of May 2018. I am hoping we can put our heads together and find a solution. I have posted on a couple other threads but starting a new on here specifically for this exact error. I...