These modems use . Windows does not have native drivers for the "Diagnostic Port" (for firmware updates) or "NMEA Port" (for GPS), but it does have native drivers for the Network Adapter .
Telkomsel often throttles during peak hours. The 300Mbps is a theoretical air link speed. To test real speed, use the Ookla server in Jakarta or Surabaya at 2 AM.
No driver can fix signal congestion. If you see 2 bars, you won't hit 300Mbps. Use a external antenna (SMA port) to force the driver to recognize a stronger signal.