1 month ago I got same
m2p behavior. My firmware was 01.00.03.00 and DJI GO 4.3.16, also I has installed NLD FCC (only FCC, no boost) - in a 1.5 km range drone suddenly lost signal with "Remote controller error" and then was circle "Connected - Disconnected" but thanx God it flyed to RTH area. One guy told me m2 works good in 4.3.14 + 01.00.03.00 and 4.3.16 + 01.00.04.00 because he losted signal like me.
Firstly I updated
m2p firm back to 01.00.04.00, keeping 4.3.16 app and do not applyed NLD. Secondly, I changed original cable between RC and phone to my ordinary phone cable (my phone is Xiaomi Mi Max 3 with QC3). And make an test flight for 3 km - no problems. After that I ordered another cable from Aliexpress and drone fly wihout problems with new cable but after ~7 flights I got similar "Diconnected" after take off and 5 sec hovering. I was out of home and try to fly another place with ordinary phone cable - all was good.
So, from my opinion, m2 can loose signal in there reasons:
1. Thin original data cable between RC and phone;
2. Conflict in versions of drone firmware and phone app;
3. Restart your phone as much times as possible (maybe it clear some extra leaked app cache);
4. NLD's FCC & boost can also be reason. For example, Jkson gived to NLD team activation commands of FCC & boost only for 01.00.01.00 firm version and no one know is they works and how for newer versions. Jkson told only NLD's FCC should work in 01.00.04.00.