Hello, I believe I've wrote a few days ago about this but the comment did not appear here. So, I have the same problem with 4g/3g signal being lost every now and then... and I missed a lot of calls because of it. My phone is bv9500 and had the March 2019 update. Now someone said here that on his bv9500pro the issue was solved by an April 2019 update. So I flashed the pro ROM on my phone (v1.0_20180829) and waiting for the update of April 2019 (but it did not appear yet). I would like to flash it if you can provide a download for it. Otherwise I question if April 2019 update for bv9500pro is the same as March2019 update for the non pro bv9500.
I request such files to tech team, we have to wait.