Mining XMR is unstable restarting randomly 1 or 2 times a day.

I have 12 rigs mining XMR, claymore-xmr-v10.2 setting :
-xpool stratum+tcp://xmr-asia1.nanopool.org:14444 -xwal .$rigName/naemail@gmail.com -xpsw x

My rigs (RX470 and RX580) settings are
RX470 : Core 1105 / Mem 2000 / Core Undervolting 850 / Power stage 4
RX570 : Core 1150 / Mem 2000 / Core Undervolting 850 / Power stage 3
I use this setting to mine ETH and ETC with no problem, but XMR.

What is wrong with my setting?
Please.