err... will knowing the admin password improve the speed? the issue seems more like signal strength. its more than 100dBm, thats too high, could be that you are too far away from the signal source or there is blockage. ang daming pwedeng reason and I doubt knowing the admin password will help. its not like getting full access to device will improve your speed drastically
better option would be to conduct signal strength test in your area (the ISP can do that ewan lang kung may bayad most likely meron)