This counts flow-control frames, both XOFF and XON, received by the device, that is, the connected switch or device asking this modem to pause or resume sending. A rising count here means something downstream on the LAN is asking this modem to throttle its transmit rate, worth investigating if the modem's own outbound traffic, like satellite-bound packets queued for uplink, is being unexpectedly delayed as a result. A steady stream of received pause frames coinciding with slower-than-expected satellite uplink throughput would point to a downstream device or switch that is the actual bottleneck, rather than the satellite link itself.