Hi Duarte, are you sure that the drag on your reel is functioning properly? If it's not super smooth you will get line breaks. 30 lb braid and steel leader should be sufficient.
Thing is if the drag is loose the fish will swim for the rocks and thats it, most of the times, i think keeping a short leash with a very strong drag might do it.
Just come back from some night fishing for barramundi and a huge fish got my rappala this was a 10 to 15 kilo it took my line for a spin around the rivermouth just to come right in front of my line of sight with a light take a huge jump of the water and probably winked as he got loose from the hook.
Shame but WOW what a sight. I left empty handed after that one no more bites.