XR60/XR80/XR90 ping IPv4 only success for a few minutes upon bootup

I have a XRxx modem using sim cards activated with ATT and Verizon data.
The modem is able to get an IPv4 from the carrier, and I was able to ping that IP address successfully but only for a few minutes upon powering up the modem. Afterwards, the ping fails 100% indefinitely (request time out).

I only have the default settings in the modem. Is this ping issue indicitative of a setting problem? If so, how should I set up the modem?

Hi @testtest,

Are you using the XR with 5G? Please ensure that antennas are properly attached to the XR. 5G cellular radio (four antenna cables required)
Please refer to the XR Hardware User Guide at the following link: https://source.sierrawireless.com/resources/airlink/hardware_reference_docs/airlink_xr_series_userguide/#sthash.3IxRTnDm.dpbs

Please check the signal strength at the location of the XR device. If the signal is weak, it may lead to a dropped connection, and you may not be able to ping.

Is the XR device currently near you? If so, you can access it locally to check the IP and network status. Also, you can provide log files to further narrow down the problem.
Please refer to the AirLink XR90 Quick Start Guide below:
https://source.sierrawireless.com/resources/airlink/hardware_reference_docs/airlink-xr90----qsg/#sthash.VSWEMr6Q.dpbs

Thanks,