What would be the cause of high ORPHAN BLOCKS

i am getting loads of them. like 70 to 80%
last 24 hours i minted 16 blocks but 12 of them ORPHAN 

i mint 1 block,  then after 2 or 3 confirmations block suddenly becomes an ORPHAN.
seems bit suspicious.

or mint 1 block and 5 active connections suddenly drops to 1 or 2 connections.
seems bit suspicious also.

All nodes coming from NOVA EXCHANGE.