What is the disconnection logic on EC21-J?

Hi, the sensitivity test on the EC21-J showed that the RSRP was not worse than on the Smartphone. However, the EC21-J clearly disconnected faster than the Smartphone. I am curious about the disconnect logic/process/decision criteria.
In addition, I tried to get the BER (Bit Error Rate) with AT command but it failed.

Hi @Yuichiro_Kuzuryu What do you mean by disconnecting?

Hi @lyman-Q Thanks for your reply.
I mean that “AT+QNWINFO” responds “No Service” and “AT+QCSQ” responds “NOSERVICE”.

Hi @Yuichiro_Kuzuryu
Thanks for your reply.Can you use AT+QENG=“SERVINGCELL” to check the network.

Hi @lyman-Q
In normal state,
+QENG: “servingcell”,“NOCONN”,“LTE”,“FDD”,440,10,22C7810,27,6100,19,3,3,1608,-111,-20,-73,-5,21

In week network condition,
+QENG: “servingcell”,“SEARCH”

Hi @Yuichiro_Kuzuryu
From the returned URC message, the wireless signal strength is very weak in the current test environment, please confirm whether the antenna is connected correctly. How is the signal on the mobile phone with the same sim card here?