I have unpacked the router yesterday. The previous firmware didn't show mobile inside the WebUI at all. So I flashed the newest firmware.
Nonetheless even with the newest available firmware the RUTX09 device is not working (also tried emergency flash using the reset button). The WebUI shows 'Modem not connected'. The router signal strength LEDs are blinking and the modem firmware version shows "N/A".
I also checked the syslog and it contains following lines:
Thu Oct 22 10:26:33 2020 daemon.info gsmd: gsmd[src/gsmd.c:find_modem_vidpid_by_id():633]: Modem not found...
Thu Oct 22 10:26:33 2020 daemon.info gsmd: gsmd[src/gsmd.c:exec_cmd():520]: Modem not found...
Thu Oct 22 10:26:33 2020 daemon.err uhttpd: Failed to invoke a gsmd object method
gsmctl doesn't work at all.
I have also tried to flash the EG06ELAR03A05M4G mentioned inside another thread, however the quectelFlasher reports, that the /dev/ttyUSB0 is missing ('ls /dev' confirms that).