Hello!
It seems that the IC in charge of that task (usually wifi and bluetooth are going right) is damaged or is "separating" from the motherboard. The only solution is to change it (I do not advise reflow)
You need a technician specialized in that type of repairs or it will hurt more than repair. It is a delicate repair and you need tools and many hours of training to do it. I advise you to look for a specialized technician in your area or request a quote from a partner of iFixit.