We are using the EG21GGB, running firmware EG21GGBR07A11M1G. I’m investigating an issue of inconsistent attachment. One thing I see is that the SINR appears very low, somewhere around 0 dB. It also bounces around randomly, for instance here are some readings taken in rapid succession:

+QENG: “servingcell”,“NOCONN”,“LTE”,“FDD”,302,610,3409F00,376,2325,4,4,4,2BDD,-103,-15,-69,1,-
+QENG: “servingcell”,“NOCONN”,“LTE”,“FDD”,302,610,3409F00,376,2325,4,4,4,2BDD,-103,-13,-71,5,-
+QENG: “servingcell”,“NOCONN”,“LTE”,“FDD”,302,610,3409F00,376,2325,4,4,4,2BDD,-103,-15,-68,-1,-

Moving to a different location I see that RSRP improves, but SINR does not:

+QENG: “servingcell”,“NOCONN”,“LTE”,“FDD”,302,610,3409F00,376,2325,4,4,4,2BDD,-97,-14,-64,3,-
+QENG: “servingcell”,“NOCONN”,“LTE”,“FDD”,302,610,3409F00,376,2325,4,4,4,2BDD,-97,-15,-64,3,-
+QENG: “servingcell”,“NOCONN”,“LTE”,“FDD”,302,610,3409F00,376,2325,4,4,4,2BDD,-96,-15,-61,-2,-

From what I read online, SINR should be above 13 dB for a good connection, is that right? I’ve tried different antennas and see similar results with both. Can you recommend other things to check?

Low SINR means that there is interference in the network environment. It is recommended to change to a location with better signal. You can also replace other SIM cards to check whether the low SINR keeps appearing.