Chosen Solution
4 months ago Apple has replaced me my 5s with a regenerated, a few days often go under any service and does not take the 3G network .. I tried to replace the antenna but the problem remains ..
The initial iOS 10 release had some serious network issues. Update to the latest iOS version and see if that helps. Otherwise, there isn’t a whole lot that can break on a phone that affects signal. You say you tried to replace the antenna, did you run into any problems? Did you notice any signs of water damage? Unfortunately, Apple has been caught replacing phones with refurbished, poor quality, water damaged replacements.
