f81a2720_ings___4G_LTE_Mobile_Broadband__Description
[light] MODE [Mode light] Blue [Description] 
This light is a constant blue, when the modem is connected to the 4G network, but no data is transferred. The indicator light flashes blue when data is being transferred.
HUAWEI B593 4G LTE CPE Industrial Wireless Router Specs, Features and Settings | 4G LTE Mobile Broadband
Description