Intermittent light - Night sky Redcliffe Qld

Looking straight up then about 5 degrees north and west from Redcliffe, a light at very high altitude would shine for about 2 seconds like a very bright star then fade to disappear for about 10 to 30 seconds then re-appear. Sometimes as bright as a normal star but often much brighter, with noticeable and gradual increase in brightness then fading away. This continued for about 10 - 15 minutes. It appeared to be fairly stationary when illuminated but reappeared slightly more north each time - not at plane or satellite speed, very gradually. Drone? Weather balloon? At 55 years old and a regular sky gazer, I have not seen anything like this before.