I also had a lot of drop offs with with ZS and I was almost ready to give up. Then, I found this on a ZS forum and my ZS is rock solid since (I did it 1 year ago) : Of the top of my head :
1) I Configure my router to reserve a local IP address to be used by the ZS
2) I Configure the ZS to use the reserved IP address and a Google DNS (server 1: enter 8.8.8.8, server 2 : 8.8.4.4)
Do not know if it will work for you...but it worked for me. Good luck.