Modem connects - sometimes

Hello, I’m using a Sixfab SIM with a KuWfi CPE LTE 4G modem.
The problem is that it does not connect to the Internet every time it boots up. It does actually connect to the provider (which I’m assuming is T-Mobile, I’m in the US) and is assigned a WAN IP address, but most times the DATA light on the modem does not light up, indicating no Internet connection. The interesting thing is that is does connect sometimes, but once rebooted it does not connect again. Trying to get some insight into possible causes - thanks.