I own a RUT241 with FW RUT2M_R_00.07.06.1, and the mobile RSSI periodically drops from -70 to -111dBm for no reason:
When the signal drops to -111dBm, all signal level LED are also turned off, but the mobile connection stays active (no disconnection).
Let me know if I you need debug logs to track this bug.
I’m using the power adapter that was provided with the router.
My RUT950 is connected to the same operator on the same BTS, and shows a much stable connection: